Any of the Qualcomm DragonBoards will perform considerably better than any i.MX8 chipset board AFAIK. Freedreno (Qualcomm Adreno driver in Mesa) is a lot farther along than Etnaviv for the time being. There's also v4l2-based hardware video decode in upstream kernels for (supported) Qualcomm chipsets.
If you want a non-Intel desktop, you could also look to any of the high-performance AArch64 or Power boards with PCIe slots in them, and slot Radeon in.
I would rather support a chip maker with open hardware, even if currently not the most performant, than one which does nothing and relies on a crowd of volunteers to make it work.
If you want a non-Intel desktop, you could also look to any of the high-performance AArch64 or Power boards with PCIe slots in them, and slot Radeon in.