Mobile games usually get a bad rep as they’re usually asset flips and/or MTX-ridden and/or ad-filled, etc., and I’m sure this is actually the case for most games on the app/play store. But are there any ones that are actually good, maybe just something to pass the time with?
Tetris.
Maybe it’s not what you’re looking for, but classics are classics for a reason. If you’re on anything remotely standard you can find a port.