note: you don't need bela pepper, trill will work with Arduino or anything with i2c the main consideration for me, is using something that can have as many cv outputs as possible.
im wondering about doing it is own small 'skiff'.
one aspect that is useful, is the trill is very shallow, this means the Arduino or whatever is doing the interfacing can sit underneath the playing surface, so it doesn't take up anymore HP than the playing surface. (unlike in this video where the pepper is a 'generic module' , so is fairly bulky)
another option im considering, is a making this skiff both AE and eurorack compatible and self powered. easy enough, as I will restrict the eurorack side to 5v. possibly using a small ribbon cable, and a tiny output module in the AE rack … as ive done previously with bela)