Mine is Local Send which is a FOSS alternative similar to air drop that works across a variety of devices.
I just installed Jellyfin on my Raspi 4 and I’m not happy. It’s so laggy and slow I can barely use it. What is your setup?
A Raspberry PI should be fine for direct play, but it doesn’t really have the processing power to transcode. Check to see which mode you’re in.
If you want the ability to live transcode, you’d probably have better luck with an old laptop or PC with a dedicated GPU (Even the lowest end ones have the same video encoding hardware in each generation, I use a GTX 1050).
Or a somewhat recent Intel Computer, maybe around 2017 onwards or even older. It can absolutely be a low-tier device As long as the processor has Intel Quicksync it’ll be a breeze to do live transcoding. No dedicated graphics necessary!
Your pi is the problem if you are trying to playback incompatible H.265 content or stuff with incompatible subtitles like SSA-subtitles in anime.
My advice (if you can) get a mini-pc like a NUC (used or new) and do everything you did on the Pi.
Besides that, watch tutorials on how to set it up properly or take your time to get docker to know. With docker you’ll just need to set up video permissions and the rest is taken care of by the container.