We don't have an official guide for setting up GPU acceleration with unraid. But guides exist on the internet for other apps that also can be applied to Jellyfin.
Jellyfin 10.10.0 (Docker)
Ubuntu 24.04 LTS
Intel i3 12100
Intel Arc A380
OS drive - SK Hynix P41 1TB
Storage
3x WD Red Pro 6TB CMR in RAIDZ1 (JF Library)