Wanted to post this here in case anyone else is thinking of going down the same rabbit hole as I did relating to using this kernel & getting hardware transcoding in Plex on a 9th gen Intel.
First - the good!
The kernel works great -- I've had no issues with it. I have a 9700k, and the iGPU is recognized and loads fine. No issues there. I can pass it to the intel gpu tools docker container and it's recognized without issue.
Plex's transcoder doesn't support 9th gen intels with hardware transcoding on Linux. They're working on supporting it though. See - https://forums.plex.tv/t/hardware-accelerated-streaming-not-working-i9-9900k/446150/2