It is still GNM and GNMX, Playstation doesn't no Vulkan, and I am quite sure that just like with MoltenVK and DXVK, not everything can be mapped in a transparent way.
That's kinda a Sony problem. The best an Open Source project can do is build HLSL/SPIR-V IR and let you do the rest yourself. I don't really know what you're asking for besides that, it's how things have been since the PS4 launched.
Besides, for the scale of games currently coming out of Bevy, you should be able to use Vulkan to pipe your game into a PS port.