I tried to [rework this by taking advantage of win32u adapters cache](https://gitlab.winehq.org/Saancreed/wine/-/commit/89925539b6400ecf6243814c7c...) but it appears that on my machine nothing ever adds my Nvidia GPU to that list. No matter if I'm currently using winex11 or winewayland, it contains only one entry (corresponding to my Intel GPU), which frankly would make this entire patchset worthless.
Of course, while this points to a bug where not all GPUs are properly detected somewhere else (which will hopefully be fixed one day), this makes avoiding Vulkan calls in GDI driver unfeasible and probably not worth pursuing for as long as the issue remains.