Composition on the spot! Training not required I like that you're mixing tonality. It's expressive. One really fun trick, if you are looking for something to add some extra weight in certain parts, is to use your thumb to cover more than one note. You'll be able to play mad clusters all over the place! Keep at it.
To clarify a bit more, be sure to try it out with both hands. I said "thumb" when I should have made it plural. It can be liberating, because when, say, an F & G, or just any 2 notes next to one another, are being struck by the thumb, it sounds chord-y enough often with just 2 notes. You could be holding down something and have the other 4 fingers doing any number of combinations to give a passage, piece, or even just a couple repeated groupings, and be playing all kinds of colorings (excluding normally the 2 notes covered by a thumb...I think even 3 notes at a time is very possible, if you work in part of your palm. I'm not joking! It is a noodling experiment. It's just kind of strange to read the process back to myself at the moment. The exception is that you could always cross hands, as well, and hold those notes down with the other hand while your more dominant hand--unless you're about even with both on piano, as I did notice that you were quite balanced on both sides in many instances...then maybe this won't apply--but, if you use your more dominant hand for a particular kind of movement on the piano that you'd really like to emphasize, doing a crossover could be very useful. I went off-topic regarding using thumbs or palms to hold down several notes at once in order to free up the other 4 fingers to add layers/parts into passages).
I'm very much wishing I just had a video to show how I wish to respond, but am not organized enough to do in depth via typing. You're really a natural when it comes to understanding how to work in variation. So, you think like a composer. Until I can finally make a video on this and hope no one on youtube really minds it much attention because I don't want to be laughed at for awkwardness in speaking through things and/or how weird my technique would look. But, basically, if there were something less specific to completely focus on (the thumbs/palms technique probably will take a lot of time to feel at ease with! I thought I'd catch on to it right away, but changing one's body control is required, and certain muscles (I think, at least!) seem to become necessary to develop. But, if you figure out efficient ways to maneuver right off the bat, that would not be surprising, because of everyone having different processes. However, should there be some awkwardness, try maybe not thinking about any specific keys, and, instead, choose different regions on the piano, and just kind of switch around. It can make a colorful fill in between melodic lines, too! If you take your fingertips and put them on the top keys/accidentals keys, and then slide down to the bottom row of notes, you could play 2 sets of fast note cluster movement really fast for each hand by alternating hand and doing a slide from the top row of keys to the bottom row in pretty much one motion, like you're swiping some dust off of something, pulling your hands in your direction, doing so with one hand and then mirroring it with the other in whichever region of the piano you choose for color or any other reasons like weight, texture, frequency combinations that you like, etc... do one swipe one hand, then another with the other, and then try doing the technique for a more prolonged amount of time. It's kind of like painting the paino.
Actually, I just got an idea to use paint brushes on my keyboad! Or, it's a digital practice piano. It has decent weighting of the keys, but getting near real pianos is always great. But, like you describe yourself, I also do spend a lot of time away from very public settings, though our reasons may be different. I think that sensory overload is the top reason I find myself the most comfortable staying in. I miss working things out with people, but I have found a friend who uses processes when he plays that I appreciate and can identify with, and he's also a good friend, and so I have tried to stay on a routine of playing every Tuesday--as a goal. Things happen, but it is still the default day. I had to move to today because yesterday, I just couldn't get up the energy to go improvise due to a somewhat disturbed sleep routine, so we switched to today. It's been helpful, although I have sometimes gone 2 months without having played music with him, and sometimes up to 3 or 4 weeks without interaction. It's just tough. Anyhow, improvisation can sure be helpful in breaking up time and getting to use your mind and figure out music strategies. So, it is pretty fun to wander the piano. I think that you can improve a great deal because you are a musical self-taught player, or, the majority self-taught. I'm sure that you've learned through osmosis, as well, which actually is training, in a way! Just a different one. Keep doing what you're doing, but maybe start taking more risks! My suggestions are just 2 or 3 of a whole bunch of things you could try.
If you think it would help, perhaps "active listening", where you could even record yourself doing so -- meaning, you interact with other sources and play parts over them, and listen to the result. If you are a visually-oriented person, another good prompt would be to look at something. Anything, really. But, a music visualizer on a player of some sort, or maybe a screen saver, you could play to that motion and just respond viscerally and even without any strict parameters in terms of caring about the notes and/or their relation to each other. Practicing different expressive movements without even caring a lick about the notes can be absolutely a great way to teach yourself to be confident in playing the entire range of the instrument! Have fun!! I think you are, and that is why you've posted these. The more varieties of ways you can get yourself to play piano, to prompt yourself to improvise, the more you'll notice you are improving all the time. Take care! Oh, and, if you learn some snare drum sticking patterns and can tap them out, they're great to use on piano if you want to get some more accents into your patterns. Okay, sorry to keep this way too long. But, I'm not sorry about responding...just about the possible eyestrain from reading through this. I hope that does not happen, though! When someone asks for advice, I sometimes pause if it is something that I actually could have ideas for, and then I don't answer, because long-winded answers are the norm. But, I'm inspired by and fascinated by improvisation and the endless stacks and piles of processes that are involved, including how the senses can be involved, and I just can't help but talk about how much I like to think about improvisation. If I think of anything more specific, I shall update this. Anyhow, I think the inventiveness is there, for you, so the best thing is to find ways to make sure that you can try to play as often as possible, including through creative slumps or walls in terms of something more on the technical side--or, both of those things, which is never fun when it's a double-slump! But, just generate ideas that will make you play, because then, by self-designing these things, you can try and work the improvisation into processes outside of playing, itself. Such as...read text, and play the text on the instrument. I think Coltrane looked at a passage of text for A Love Supreme, although I am not entirely sure I'm remembering the correct recording. Have fun, Ardoire! Take care, too. Part of my strong response was the reclusive part, and the fact that most of my family, although they're supportive and appreciative, isn't one with musicians. However, my cousin's son actually has a really great sound and he's a baby, so there may be her husband's (a musician) influence. I'd talk with him about it, except they live far away and he's busy with a demanding job. He's self-taught and talented, too. Actually, he's technically family. But, no immediate nearby family to discuss music with too much because I tend to confuse them, and I don't want them to feel bad that they don't understand.
See, your videos prompted all of this! Life is too intense, even communicating online is. So, I just tend to feel better by spending a decent amount of time making sure there isn't any stress. Unfortunately, I'm not close to nailing the whole concept of inspiring myself to play that I was trying to suggest for you to consider expanding if you hadn't been, already. When I'm stressed, I cannot be near an instrument!! So, I have spent a lot of time just jotting down ideas for the next time I improvise. Am probably at about 3 or 4 times a week of extended playing, so not every day as I'd ultimately prefer. But, I am trying to do little tiny mixed media art on little paper squares, and have been trying to inspire music with one/or, vice-verse--inspire art with the other. All depending.