Linux mitigates this ;)

There's this:

https://goldilocklabs.com/products/silentglass

And this:

https://git.cuvoodoo.info/kingkevin/board/src/branch/hdmi_fi...

But I'm not sure they would block it, and the latter is not plug-and-play.

I expect it wouldn't be especially hard to make one though.

The issue here isn't unwanted communication between the monitor and PC but rather the PC doing unwanted things in response to a specific model/brand of monitor. To work around this you would have to change what model the PC thinks the monitor is.

Would it be as simple as spoofing the EDID manufacturer/product to something generic? I naively assume DCC/CI would all still work?

I’d certainly expect so.

There are cheap dongles that spoof the EDID for a fixed 4K or HD monitor with fixed settings. Not sure what they do about DCC/CI, might just disconnect it.