Tips wanted for HTPC with Nvidia GPU

I was thinking about maybe getting a Steam Machine, but since I didn't get into the reservation list, I decided to build my own. I have an RTX 2080 left over from upgrading that nobody wanted on ebay so I will use it in that build. Since my TV supports VRR I want to use that and in home streaming for demanding games is fine for me. Ideally I want to use CEC as well, I got a DP to HDMI cable from Cablematters that supposedly can do that. I have SteamOS on my handheld PC and had Bazzite on it for several months, so I am used to some tinkering on Linux by now.

Now my questions:

• I would like to use this as a HTPC, so it should be a controller first interface. Afaik Nvidia GPUs don't work at all with SteamOS. Are Bazzite-deck-nvidia or CachyOS Handheld editions a reasonable choice? Should I just go with a desktop edition of some distro with Wayland and use big picture?
• I know how to add firefox bookmarks as non-steam games to Steam. I want to use the PC to watch YouTube and Prime Video etc. Is there anything I can do to improve video quality?
• Will wake on USB with the Steam Controller puck work on any distro?
• Should I be using something different if I want to use streaming services as well as gaming?
• Any other tips for HTPC builds? (mostly software/UX wise, because hardware is already on the way)