I'd love to use Jellyfin instead of Plex, but the LG webOS client has literally never been updated. The first public version from July 2022 is still the latest version, and it's not really there yet.
Honestly it's been a year since I tried it now so I don't remember everything. One thing I really feel is crucial is turning down subtitle brightness in HDR. Plex allows for grey subtitles, which in HDR look white, except not at 700+ nits. They literally light up the room in dark scenes, and it's extremely jarring in dark scenes (with APL of 1 nit or less).
@anthonylavado I would love an "app" for the Vidaa OS on my HiSense TV. I can use the one on the FireTV stick but that's now the only reason I still have one LOL