Short version: Mobile games are different licenses. Emulation on mobile devices have its limits.

Steam sells PC games.

Mobile devices are not designed to play PC games.

You mean this?
https://test1.login.steam.hlxgame.cc/discussions/forum/10/679607959154682093/

Originally posted by littledinobro:

Well for like people on moblie should be able to play their games on their device.

So install Steam Link on your phone and stream it.

What stops you? You have both, apps like winlator or winboat, and native terminal app with full linux distro built into your android OS, now with graphical acceleration. If your device is powerful enough to run any game from the last 15 years is questionable, but that's on you.