Gaming on Linux with an AMD Radeon HD 7770 or similar

You may know that AMD cards are supported surprisingly well on Linux, because AMD is adding their drivers directly to the Linux kernel. These cards are also the only option on Linux right now to have good performance with direct rendering over Mesa and Wayland support.

Games over Proton are complaining about missing DirectX

These cards usually support DirectX up to version 11 which is recent enough to run most if not all game titles. The problem here is that the driver has experimental features disabled by default which are needed to run games over DXVK which is the layer to translate between Vulkan and DirectX calls to your GPU. To enable these experimental features all you have to do is to append the following to your kernel parameters.

radeon.si_support=0 amdgpu.si_support=1

This workaround was taken from https://steamcommunity.com/app/221410/discussions/0/1736589519991366130/ after a long and horrible internet search finding a solution to my problem.