Hi ,
Windows Server Hyper-V use Discrete Device Assignment (DDA) as an alternative. However, for windows 10, DDA is not support.
As far as I know, Microsoft has not published a replacement for RemoteFX in windows 10 hyper-v so far, I would suggest we could wait to see if any documents would be published in the future.
As a workaround, you might try to add it via Powershell:
1) Check your Host GPU (You need RemoteFX Compatible GPU Card and Remote Desktop Virtualization Host role)
Get-VMRemoteFXPhysicalVideoAdapter
CompatibleForVirtualization: True
Enabled: True
2) Enable/Disable Host GPU for RemoteFX vGPU
Disable/Enable-VMRemoteFXPhysicalVideoAdapter
3) Add RemoteFX vGPU to your VM:
Add-VMRemoteFx3dVideoAdapter -VMName <vmname>
4) Open VM Settings dialogbox, you can configure RemoteFX vGPU.
5) Start VM
Here is a thread discussed before , please have a look:
HyperV "RemoteFX 3D Video adapter" gone in Windows 10 1809
Best Regards,