There are distributions with a great Steam experience out of the box? It’s SteamOS actually a good choice? Maybe isn’t what you use or prefer.
A good Steam distro for me has a very mininal procedure for perfectly working controllers, client and general user experience.
Your direct test and experience are very appreciated.
The Linux Experiment did a video on how he managed to turn a PC to a console with HoloOS (its not a step by step guide though)