I'm interested in knowing if any motherboard brand has been able to load it.
With a B450, I am able to load the ccp module, but just as you, run into the same error. Because of ccp, ccp_crypto cannot load, and because of that, kvm_amd cannot load with parameter sev=1.
What's interesting now is that the kernel can load with mem_encrypt=on where it used to freeze, so at least part of AMD's security functions work.
There is also this commit to the linux-firmware binary blobs:
I have tried building it into my kernel for a Zen 2 processor but ccp returns the same error. I would like to try and just remove the register check but I don't know the extent of damage I could incur with that.