Nushell is pretty nice.

For Rocket league you need to manually enable proton under properties.

Its running without problems for me now

As long as you arent doing anything to advanced nix is basically only a configuration languages. You probably have to make heavy use of the option search to know where and what to configure

AFAIK steam has optional drm. If the devs dont use it you can play the games without steam. I think it says on the store page if it’s drm-free