Well , it seems that it doesnt work on AMD lower than RDNA2, the only way to test the Vulkan in AW2 is to try it under linux and see if it brings any fps uplift , but that will be minor uplift for the struggle of doing it if you are not already on linux, only hope is that maybe it will work with future driver and DLLs updates but i wont bet on this, maybe it works with some other games (or future games) or if people with AMD cards will still experiment with the MOD maybe they will find a way to make it work or maybe there is someone that wants to dig deeper and has time to try fixing this in the code as its open source and you can compile the dlls yourself.
The people with GTX 1070/80 TI at least can enjoy a 30fps + on 1080p with FSR on Quality if they really want to play AW2 and they dont want to upgrade to a new GPU yet. I mostly did this of curiosity , hopping i could find a quick way to make the game playable for people with unsupported GPUs and im not the coder of those DLLs so its not much i can do about it nor i think that something like this could be a game changer in any way to worth investing too much time into , just a little hack to play with.
The idea behind it is more like to be able to play a DX12 game that wont start on older GPUs rather than improving the FPS or just to test a "how the performance would have been" if some game had Vulkan support, in general this should drop the performance as it adds another layer but could also maybe improve the FPS over DX in some cases. As i wrote in the main post: Speculation: the FPS boost using this MOD in Alan Wake 2 might be only because with the MOD Post Processing Quality is completely disabled (you can only set it to LOW in the game on DX12 , is gray out when using the MOD), maybe Vulkan API helps a bit too, i dont know, also using higher texture resolution might not affect performance but will give you better visuals (if vram usage is not over the limit).
Some info about this mod performance on linux for AMD GPUs:
"Given the game seems to reach even 60 fps on 5700 XT on Linux, as opposed to Window's ~30, you'd be better of trying it on Linux.
Polaris GCN4 seems to be absolutely DOA on this game, but Vega reaches ~17 fps on 1080p Low, FSR2 Quality? You'd probably reach 30 on Linux, maybe with a more agresive upscale.
VKD3D doesn't really work on AMD GPUs on Windows, as opposed to Nvidia, for some reason."