See my comment below. Apple needs to fix this already. HiDPi does work on the M1 macs, it just is not consistent. For me it randomly works when I override the PropertyList. It could be a hardware issue, but I honestly think a software patch should be able to fix this issue for us.

One other thing to note, when changing the PropertyList, the name of the monitor always changes upon reboot. So the PropertyList is being read on the M1 Macs. As for why the rest of the PropertyList isnt being registered regularly, that is up for the developers to figure out. I wish i could figure out exactly how to retrigger HiDPi, but it happens when I'm not trying to trigger it.

Ok so weird.. One other thing to note, I also used https://github.com/xzhih/one-key-hidpi however it only seems to create DisplayVendorID-0 and DisplayProductID-0. HiDPi wasnt working again, then I changed HDMI ports on the TV. Name of TV reverted back to default "SONY TV *00", but now it is giving me HiDPI. Not sure if it is my old DisplayProductID kicking in or "-0" from one-key-hidpi. All I can say is that it is working.. however I am not getting "Billions" in colors anymore, only "millions".