Zero information how Rpi5 and the Radeon GPU are hooked up together, as if a port magically appeared out of nowhere to make this setup a total breeze.
I guess you could use the m.2 HAT to have a PCIe connection to an eGPU, but a PCIe 2.0 1x lane (500 MB/sec) is laughably inadequate for a video card - how do they get around that?