I have AMD hardware acceleration working for Plex in an LXC container with an AMD APU so I’d assume it’s possible.
Tdarr seems to use ffmpeg under the covers, so I’d focus on getting that working with amd. If I remember I had to install the mesa drivers and pass in the /dev/dri folder. Then you can check ffmpeg for the amf encoders (AMD media framework).
I’m guessing it’s a cuckold fetish at this point.