I got a LittleBits synth kit a few years ago, it’s instructional, fun and nicely done.
After a while though, I thought I would like to have more control over it, to sync it with other things, or to play it from a proper keyboard.
There’s no MIDI input supplied; there used to be a module available, but discontinued I think, fortunately somebody else has tried:
https://www.instructables.com/USB-MIDI-Littlebits-synth
I’m going to build this as is, then modify, seeing how flexible it can be, and maybe building an enclosure