[cben]

Radxa X4 board specifically has x86 N100, an M.2 slot (a short one) and GPIO (though you need to flash the on-board RP2040 to access them? haven't tried yet). I'm quite happy with it as a cheap desktop. Documentation is pretty OK? Nowhere like the tutorials ecosystem around RPi but Radxa are certainly trying to provide detailed info.

One sweet quality of RPi this lacks was being unbrickable — the entire state was on SD card; screw up and you can just write a new card. (Recent RPis complicate that with an a boot flash). But by now I've bricked enough RPis by electrical damage — including an 400 — to not be as excited about that :-]

I do agree with your analysis. All I'm saying is if one is considering a competitor, the X4 with x86 running mainline linux might be a safer bet than most less-documented ARM boards...