Hi gang, I was bale to find the solution to transcode in Jellyfin with an AMD 2200G and any other AMD CPU/GPU combined.
Make sure you have installed the firmware-amd-graphics package for your AMD CPU/GPU under OpenMediaVault. (sudo apt install firmware-amd-graphics).
You need to add the Linuxserver Mod in the docker-compose, https://mods.linuxserver.io/?mod=jellyfin, which installs the latest Mesa libraries in your docker container.
I added the group_add line, as per instructions from the Jellyfin web page, in my docker-compose by viewing the output from the /etc/group using command cat /etc/group and looking for entry render. Mine was render:x:107:.
Just to make sure, some folks have found that changing the access mode for the /dev/dri group helps. Here is the command, chmod -R 777 /dev/dri/
Here is the docker-compose that I used to make it work.
Here is the link to the Jellyfin web page which explains how to add hardware transcoding for AMD CPU/GPU.
Hope it works out for you.
Now if only Plex would work with AMD CPU/GPU.