Bear in mind that in-video ads that Google is experimenting with will still cause 403 errors. There is another bug report for that. However, this fixes most playback issues.
I run an HTPC that works fully with my AirMouse Remote I bought for it for ~$15USD. It uses Flex Launcher running on Debian.
Basically, I use it for Plex, some Netflix, retrogaming, and Steam.
I was in a similar boat to you were I looked at Plasma Big Screen, LibreElec, etc. Plasma BigScreen was too buggy or unmaintained. LibreElec is great if you want to play local stuff, but terrible for streaming things like Netflix. In the end I said "screw it. I'll make my own". Now it's the center of my living room.
I mean you could say the Steam Deck is "just KDE on Arch".
The difference is how they implement it and what it's used for. This could be huge for "apps" on the Steam Deck, for example. Or it could be a quirky experiment or feature nobody uses. Time will tell.
I was speaking of the gaming industry as a whole. I know very little about this developer. Perhaps they're one of the good ones swept up in unfortunate-ness.
It's from Google intentionally breaking things