What is the plan on MIDI exports currently? Will they be Format 1 (all instruments saved to different tracks) or Format 0 (all instruments saved to a single track) (Coming from Finale in case you couldn’t guess.)
Also, I tried Notion for a little while and their MIDI exports, unfortunately, don’t work too well. All instruments are saved to one track and no matter what the key signature of your piece is, it saves the MIDI to 4/4. Using this export as a MIDI accompaniment on a Yamaha piano made the file almost unusable. It sounded great, but I could never start in the middle of the song somewhere since I couldn’t see where my measures should be.