Yes RemoteFX vGPU has been removed but other RemoteFX options persist, in particular the media streaming.
GPO options
– Compression for RemoteFX Data
– Image quality for RemoteFX graphics
How these options integrate with “prioritize H264” is clear as mud…
(BTW I don’t think ThinOS 8 is based on Windows. At least the RDP stack, including RemoteFX is entirely proprietary / closed source. For ThinOS 9 the stack is provided by Microsoft AVD, only packaged by Dell for ThinOS 9)