If you like this kind of thing, The 8-Bit Guy has a great YouTube channel covering how this kind of thing worked in general, including a video specifically on CGA color on composite monitors (the high-level way this hack works), which touches on this (and taught me a bit about why some of the CGA games I knew growing up looked the specific brand of funky they did).
Alas, I’ve lost the link, but there’s also a cool hack that replaces a Nintendo cartridge with a “dynamic” rom to achieve graphics beyond the reach of the original hardware.
Possibly https://www.youtube.com/watch?v=ar9WRwCiSr0 ?
Yes! I didn’t remember it seeing it on YouTube, but now I realize why: I saw it in person at deconstruct.
Oh this brings back memories of hacking the CGA card, but nothing like what this person does. Very nice!