I’m tired of hearing about Apple dropping eGPU as if it was deliberate, so allow me to speculate on this: the ARM PCIe IP does not support legacy I/O or Thunderbolt, and I think that is what the M1 is using. Thread.

I think you will find if you look at the Mac Mini motherboard, two PCIe lanes come out of the M1 SoC to perhaps two Intel Thunderbolt chips. And this is why you can’t chain displays right now. No native Thunderbolt.

Now, the question is if Apple wants to kill eGPU or not, and I think this might be easy to check. If the AArch64 AMD kext is present but it just doesn’t work, it’s probably that the current PCIe IP doesn’t support legacy I/O. If the kext isn’t there, they might want to kill eGPU.

My bet is that a nice PCIe/Thunderbolt IP is in the works for the next chip and when it shows up eGPU and chained displays will just “light up” on that platform.