Most proton games work flawlessly on steamdeck. The only issues after almost a year I encoutnered are related to anti-cheat and DRM.
You can dock it with any hub that supports 45W usb c power and hdmi. There are lot of docks and valid cables online - it's really not that difficult to get it.
So far Valve's support has been great and I'm not sure I agree that their infamous for abandoning hardware. The steam link has been merged into as a software project and steam controller still receives support though is no longer in production.
And ironically some games work better on Proton, partly because Wine shipped fixes for them (like RollerCoaster Tycoon 2) or Valve fixing game bugs on the Proton side (Elden Ring shader compilation stutters come to mind).
You can dock it with any hub that supports 45W usb c power and hdmi. There are lot of docks and valid cables online - it's really not that difficult to get it.
So far Valve's support has been great and I'm not sure I agree that their infamous for abandoning hardware. The steam link has been merged into as a software project and steam controller still receives support though is no longer in production.