Sound is tricky and very involved, to get and do right without getting quickly annoying. I imagine most people would probably play without sound anyway, so it probably just doesn't seem as worth-it. A mod could certainly be doable, though! I'm not sure where someone could begin with trying to link sound effects to cheeks plapping, but it might be possible. But yeah, a huge undertaking to implement. If you feel a great need for it, maybe try to learn it and implement yourself? c: Godot is open source and fairly easy to get started with, and Rahi has a little wiki with some information for getting started.