Nothing is stopping you from switching right away. It's not as hard. You can check whether the games you are interested in are supported on protondb
I'm waiting until there's a big download button on a Valve page, and ideally a supported upgrade path from an existing Windows install.
Use any low maintenance Linux distro and install Steam through flatpak and you got the exact experience you want. There is no difference. You are waiting for something which might never come out so that installing might be 10 minutes faster. That is totally absurd.
Steam OS ist not more maintenance than any other low maintenance distro.
Kernel level anti-cheat is unethical and dangerous. The sign-ins are mostly spyware.