There was a HDR hackfest earlier this year. A couple of reports from after the event if you're interested https://emersion.fr/blog/2023/hdr-hackfest-wrap-up/ + https://blogs.gnome.org/shell-dev/2023/05/04/vivid-colors-in-brno/. It also got a brief mention in the System76 blog https://blog.system76.com/post/may-flowers-spring-cosmic-showers.

So it's being worked on, and it seems all involved are trying to get it right - it sounds like gamescope on SteamOS doesn't need to worry about solving all the problems that general purpose desktop compositors will have to.

But the Steam Deck doesn’t use Wayland so it shouldn’t be an issue

Desktop mode doesn't yet, game mode does.

https://www.protondb.com/app/1105510

It's marked as unsupported by Valve, but as others have mentioned people are successfully playing it using Proton-GE instead of stock Proton. There's plenty of guides online for installing Proton GE on Deck using ProtonUp-Qt (or Wine Cellar if you use Decky Loader) if you haven't done it before.

The next release of Heroic should support Amazon - support was merged a week or two ago.

https://github.com/Heroic-Games-Launcher/HeroicGamesLauncher/pull/2831

Fedora's immutable variants are more flexible than SteamOS 3 currently is.

Fedora supports package layering (and the layered packages are reapplied on system image updates), you can pin multiple deployments and switch between them, and the ostree managed /etc is more advanced than the overlayfs setup that SteamOS uses.

SteamOS's simpler approach is perfectly fine for its intended purpose though.

Both games are classics and worth trying if you haven't played them yet. Love it when Prime Gaming gives out GOG keys.

Steam Deck doesn't currently support being the streaming host (at least, SteamOS currently doesn't - but I wouldn't recommend wiping that as it's one of the best parts of the deck).

I don't find the Steam Deck unwieldy. It is big, but the design and weight distribution makes it comfortable to hold - I don't even think about it when I get into a game on it. For comparison, I find the Switch Pro controllers very slightly smaller than I would prefer, but comfortable too, and the DualSense to be about right.

I picked up the Yakuza Collection. I played 0 on PS4 and loved it, but never got around to the others. It's one of the few games where I spent the time to complete side quests and mini games and actually enjoyed doing it.

Also got The Legend of Heroes: Trails in the Sky - I've heard good things about the Legend of Heroes series, and want to start at the beginning.

I've been very tempted to try Steins;Gate and Stray, but I'm not likely to get around to them until the next sale so will probably just leave them until then.

You might have just had bad timing - the release notes for Proton 8.0-4 mention

Fixed EA Desktop having a blank log-in window after its recent update.

It's currently a test release so should be out shortly, but if you want to use it immediately there's some info on enabling it early at https://www.gamingonlinux.com/2023/09/proton-80-4-is-now-in-testing-with-a-release-candidate/

it doesn’t support any anticheat for any major games

That's pretty strongly worded - I know Bungie and Epic (Fortnite only) have both refused, but I consider quite a few of the many games that do support anti-cheat on Proton to be major https://areweanticheatyet.com/table/1/?search=&sortOrder=&sortBy=status