I've run it on a pi 4 with no issues(streaming 1080p). If you're not casting to another device you might want to check out Kodi though.
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+1 for Kodi in this situation.
I ran it on a Ras Pi 3B+ and it did ok with 1080p and below. There were a few movies that had stuttering issues, so I'm guessing the Pi's better with some codecs than others.
Probably depends on the raspberry pi but jellyfin tends to be pretty heavy duty on its hardware requirements. You can probably get by on a modern raspi with transcoding off