1. Play notes on adjacent octaves with more keyboard keys (preferably in the style of https://www.apronus.com/music/flashpiano.htm
2. Ability to switch tuning systems from equal temperament to others to allow for microtonal melody playing such as those of Byzantine, Turkish, Arabic, and Persian music, Javanese Gamelan, etc.
3. Better sound timbre for less chiptune-y music
4. More traditional/folk/art instruments, like the hammered dulcimer (Santur), plucked zither (Gusli, Qanun, Guzheng, etc.), accordion, rattle, triangle, frame drum (Daf), etc.
5. Also this might be difficult, but the ability to vocalise in different styles, like choir style, opera style, pop style, throat singing, or even yodelling

For the Santur I actually possess one and I can record the sounds you want and send them to you

Bump