The version of mpv on Android from the f-droid repository allows swiping vertically on the right side of the screen to change the volume and swiping vertically on the left side to change the brightness. This is really handy for video playing as it's sometimes necessary to quickly change those settings. mpv on my Thinkpad Yoga with a stylus and on my PinePhonePro doesn't support this. I think that operating in the same way cross platform is what most users will expect.