For delicate melodic writing, I really like step sequencers that let you specify a duration per-step, rather than a constant pulse with rest/note triggers.
The intellijel Metropolis is the most prominent eurorack example of this style, but it only does 8-step patterns which is enough for riffs, but not great for melodic work. There’s several Buchla sequencers that can do this - the 248 and the 250 I think, but I’m not a Buchla user.
A newer module you could also look at is the Frap Tools Usta - which seems like a Buchla 250 clone in euro to me, but I haven’t gone super deep into its capabilities or workflow.
That said, it sounds like you might be past working on hardware - my oblique take would be that something like Orca, or even a tracker-style UI for detail-oriented work, might be worth considering if standard notation and piano-roll UI isn’t doing it for you.
What I’m using for this now is my OP-Z - sequences have a max of 16 steps, but you can set duration per-step, and have different step lengths and overall resolution on each track, with lots of ways to add variation and randomness.