Apple Silicon Macs and Intel Macs use the override files differently. What works on Intel Macs will not work on Apple Silicon Macs.
In the override file, you can see that it patches byte 146 of the EDID. If you get a copy of the EDID then you can compare it with the patched version to see what it is changing. This patch is part of the default override file from Apple.
I think the patch just removes
SMPTE ST2084
from the EDID but that's only in the mtdd overlay EDID, not in the tile 1 or tile 2 EDID where the patch would make them invalid. I don't know why the overlay would be patched - it could have included that change. Because of these circumstances, I can't say for sure what it does.
In the override file, you can see there are two scaled resolutions but they're actually the same (6144 x 2592). One of them has additional flags.
SwitchResX and BetterDisplay should be able to create similar scaled resolutions (without flag changes though). However, I think Apple Silicon Macs are limited to 6144 width (this is the width of the Dell 6K display) unless the EDID has a higher width added but if you add a higher width, you can't force an Apple Silicon Mac to use a lower base resolution for scaled resolutions like you can on Intel Macs?
Code:
base64 -d <<< AAAYAAAACiA= | xxd
00000000: 0000 1800 0000 0a20 .......
base64 -d <<< AAAYAAAACiAAAAAJACAAAA== | xxd
00000000: 0000 1800 0000 0a20 0000 0009 0020 0000 ....... ..... ..
printf "%d %d\n" 0x1800 0x0a20
6144 2592
echo $((6144/2)) $((2592/2))
3072 1296