By enabling libplacebo and using the 0012-Experimental-vulkan-encode.patch patch, I was able to render with a Vulkan preset for the first time. However, decoding with Vulkan still does not work for me.. The fact that ffv1_vulkan (with nv12) works but my other presets for hevc, av1, and h264 do not, does that mean I need to find the right pix_fmt for them?
Furthermore, nv12 is not suitable for ffv1, which is generally an archiving codec and requires little or no color compression. (https://trac.ffmpeg.org/ticket/11515).
I tried changing the pixel format (from the render configuration window) of your preset from nv12 to: nv16; nv24, p010,p210,y210 and y416. But the result is the same as nv12. ffprobe indicates yuv420p for the various renders.

Note: In ./configure, the “--enable-libplacebo” option does not work for me, but the “--with-libplacebo” option does.
Note2: I tried the latest appimage made for Terje, even though I don't have Intel hardware, and rendering with Vulkan doesn't work for me.