I finally just tracked down my issues. There was a recent addition to the amdgpu.ppfeaturemask kernel option, and the archwiki recommended value was enabling an

I finally just tracked down my issues. There was a recent addition to the amdgpu.ppfeaturemask kernel option, and the archwiki recommended value was enabling an unstable asynchronous mode. Additionally, there was a recent regression in the AMDGPU kernel module that's now fixed in 6.1rc2. So with a tweaked boot parameter and a manually compiled kernel, I have working suspend!