the -5v/+5v swing is the output of the oscillators, more just a warning not to plug them into any other gear that will break with negative voltage.
I use positive only CV sources with my Bugbrand all the time (Korg SQ1, beatstep pro, keystep, meng qi voltage memory, ciat lonbarde etc), most with only a 0-5v swing.
For osc pitch that’s still 5 octaves of notes and, if accurate tuning matters to you, just means you will need to tune your 0v CV to pitch the lowest possible note you may want to use as you will only be able to CV notes higher than that.