No personal experience, but you can actually get Stable Diffusion to run on AMD cards.
It uses DirectML on Windows: https://gist.github.com/averad/256c507baa3dcc9464203dc14610d... This is thanks to Microsoft, not AMD.
On Linux you can use ROCm: https://www.videogames.ai/2022/11/06/Stable-Diffusion-AMD-GP...
The horrible install processes and what a mess this is is all down to AMD.