Doesn't jellyfin still lack auto detecting hardware acceleration settings? Setting up quicksync transcode in Plex meant just mapping /dev/dri and checking use hw acceleration + use hw accelerated encoding and it just works. In jellyfin, according to the documentation (I mean just look at the size of that page... I've spent hours poring over every section trying to get my setup to work), you have to pass in the render group id in addition to passing /dev/dri, run a command inside the container to check capabilities, then it just says to "enable qsv and uncheck unsupported codecs" without any guidance on how to match the output of the command with the codec list. I kept getting playback errors so I resorted to using the Linux server docker container and referencing the Wikipedia page for quicksync to enable the codecs my CPU should be able to handle with quicksync.
They sorely need to make it just work out of the box with a single enable check box and have the rest of the settings auto detected and hidden under advanced. At least it should add (not present) or grey out every hardware acceleration device not detected like amd/nvidia on my nuc that's just Intel, and the codecs should just auto set based on your hardware and show a warning if you enable something outside of the detected capabilities. I still can't get opencl tone mapping to work despite having the opencl linuxserver mod so I've just resorted to VPP, my jellyfin users can just deal with it if it doesn't look quite right.
You can't cast to Chromecast (non-googleTV if that matters) from Firefox mobile, also pull to refresh doesn't work in browser, and they dont support push notifications for uploads. Revanced works great so I see no reason to switch, and it's based off of the official YouTube APK so you're only logging into Google play services, and you get the same native app experience you're used to with all the addons you'd get from browser extensions built in (adblock, shorts block, sponsorblock, return dislike, background play, etc.)
I don't think there's anything that YT in Firefox mobile can do that revanced can't, but revanced gives you cast support (through the official cast shim that supports CEC for pause, play, stop using the TV remote unlike doing screen mirroring of your phone where you can't use your phone for anything else while mirroring) and other niceties like notifications and one tap to newpipe player / download video file through newpipe. It's only a benefit to use revanced over the mobile web.