Proton works amazingly well for me, on my Debian install. I recommend people try it out :)
It works properly only with AMD video cards right?
You only need a GPU that works fine with Vulkan, tho, like those reported on this page (if your GPU is made by NVIDIA, ofc): https://developer.nvidia.com/vulkan-driver
On Intel iGPUs it works if it has Vulkan support but, as always, the performance isn't that good (as with any Intel iGPU).
The unique thing made by Valve that only run on AMD is ACO, a shader compiler for Vulkan that's faster than LLVM, which is used by the open-source stack