I was buying everything on gog before the steam deck, it's a bit more harder to use them on the deck but theyd5fit your use case. Anyway if the developers do not put drm on their games and do not use steam services you can copy their steam install folder between computers. I don't think it's really steam fault for something the game developer require themselves.
I went to a boardgame festival and he had a live show where they gave some people on the front the tools to follow his instruction. I remember he did a weed joke ;D
Steam uses Proton under the hood which is based on wine. From the repo
Proton is a tool for use with the Steam client which allows games which are exclusive to Windows to run on the Linux operating system. It uses Wine to facilitate this.
He also said "it's residenting evil time"