One thing to note for linux and GCN GPUs, is that older GCN based cards doesn’t use AMDGPU driver out of the box, so vulkan won’t work initially. You need a kernel parameter to enable amdgpu for older GCN (at least I’ve had to do that with arch linux). But when it is enabled it works great in my experience. You will get a warning in the console that the support for that GPU is experimental though.
Also vulkan support for Ivy Bridge is not complete and is experimental. It is unfortunately not possible to use DXVK on ivy bridge due to this.
I never had a game cube so it didn’t cross my mind. AMD’s GCN is short for “Graphics Core Next” though.