Atomic OS’s (especially Fedora based) with Nvidia are going to be a bit of a pain. Did you follow all the instructions found Here ? I personally gave up on silverblue/kinoite after I tried Bazzite. Similar bases, but the Bazzite devs paid special attention to GPU and accessory drivers/implementations that are otherwise much more painful in Fedora Atomics. You can always do a clean rebase then re-run the steps above (only the OSTree section).
Isn’t AMD’s HEVC/265 still decent, specifically? I feel like I read that somewhere years back. 264 has always been a weak spot for them, however.