Allow selection of primary GPU
Currently, the primary GPU used for rendering is selected based on boot_vga. I use a thunderbolt 3 eGPU connected to my laptop (using the amdgpu driver), and using GNOME on Wayland results in a ~30fps experience due to the overhead of using PRIME render offload over thunderbolt.
Since recent kernels now detect boot_vga properly and assign it to the intel iGPU rather than the eGPU, I have been forced to use a pretty janky hack (https://bugzilla.redhat.com/show_bug.cgi?id=1692990) to disable the iGPU completely. This causes the eGPU to be used directly, giving a smooth experience and good performance.
If GNOME/Mutter could support support selecting the primary gpu manually (or even better support rendering to different displays with different GPUs), this would allow for eGPU users to use it without janky hacks.