Adding amdgpu.gttsize=126976 and ttm.pages_limit=32505856 to the kernel parameters, while setting the VRAM in the BIOS to the minimum value, enables unified memory to work as expected on AMD Strix Halo running Linux.
The https://strixhalo.wiki has most of the info you need to get LLMs running on these machines.
I'm all in with the JetBrains love, but for clarity, you can keep the first version you paid for indefinitely not the last. So if you decide to stop paying the subscription you have to go back to a year old version.