I'm very interested to see how this turns out. I'm in the process of planning a build myself and torn on either going with an R3 5300g (when it comes out, which should be soon™, hoping it comes out early Q2/21) or something like an R3 3100 and tossing in an old RX 550X.
Your results do look promising though, and I'm glad to hear that you were able to get it to somewhat work at least temporarily. I did a search before running into this thread and there were posts going back indicating that for the 2200g and 2400g GPU passthrough wouldn't work but they never really elaborated and gave up.