I've seen a few people asking on these forums about SwitchResX not allowing the "Millions of Colors" setting on M1 Macs. I contacted the developer, Stephane Madrau. This is his response:
The video driver in the Apple silicon macs doesn't manage resolutions with 8 bit color depths (millions). There's no way to get anything else than 10 bit color depths (billions) on these Macs. It's not a limit in SwitchResX, it's the Apple way of doing things: implement new features and progressively remove previous ones. There's no way for any application to make this possible again sorry - it has to be done in the driver and only Apple can write drivers on these Macs
So it looks like the SwitchResX workaround will no longer be an option for the new, non-Intel Macs.
I have also tried importing color profiles from older MacBook Pros, and those color profiles are not even offered as options to select in the display settings.
The only workaround I have found is that when I plug the M1 into an external monitor and set the primary display to optimize for the external monitor (in my case a BENQ EW2440L) the old color profiles are available. I have always had the most luck with the PaperLike and Flux color profiles.
Color Profiles:
https://drive.google.com/file/d/1JLhiuwVt17RABvn1Ga45_caZJg4wqRdx/view?usp=sharing
https://drive.google.com/file/d/1GRjlXbiLFeYe2rJOXF0pYqJtGihX0soj/view?usp=sharing
I may try and order an external eInk monitor but I see reports of dithering in the displays. When I ordered the Dasung PaperLike before I had to return it because for any shaded part of the screen the dithering was obvious. There were dots crawling all over the screen and it made me dizzy and nauseous.
I'm still convinced that we need to petition these companies on the grounds that this is an accessibility issue. I've created a petition if anyone wants to sign.
https://chng.it/nSxDD6WRg7