It is increasingly rare for EDK2 (A modern, feature-rich, cross-platform firmware development environment for the UEFI and PI specifications from www.uefi.org: https://github.com/tianocore/edk2) to not be used as the basis for a secure boot load plus runtime firmware services stack).

Vendor veerage from vanilla upstream edk2 does occur of course but it does so also with legacy BIOS’. There’s no getting around it in the real world with very very few exceptions.

UEFI evolved to solve standardized boot and firmware at scale and the internet as it stands today would struggle without a standard like it. RISC-V taking a different approach would be swimming against the tide backwards to irrelevance.