IF your Radeon VII is recently manufactured it should be UEFI compatible.
Found this previous Tom's Hardware thread asking the very same question as you are: AMD Radeon VII Lacks UEFI Support, AMD Responds (Updated) | Tom's Hardware
It mentions that when the Radeon VII came out, some of the GPUs may have had BIOS that were not UEFI compatible. but AMD sent new vBIOS to replace the ones that weren't UEFI compatible.
If by a very slim chance your Radeon VII is one with the non-compatible BIOS you can download the correct vBIOS and install it.
This Radeon VII vBIOS v106 from TechPowerUP is UEFI compatible: VGA Bios Collection: AMD Radeon VII 16 GB | TechPowerUp .
I believe version 106 was the latest vBIOS to make the GPU card UEFI compatible.
