So I am overriding the PropertyList with my M1 Mac mini, macOS Monterey, and my Sony Bravia XBR43X800D. This is not known to work, but occasionally it still does. It is random, like when my tv is off for a while then I turn it on. Kind of confused why this is happening, but every once in a while HiDPi works again. When HiDPi works, I actually see "Billions" for colors instead of "Millions" in addition to getting full 4k.
https://codeclou.github.io/Display-Override-PropertyList-File-Parser-and-Generator-with-HiDPI-Support-For-Scaled-Resolutions/