That would definitely make cycle accuracy easier between all the system parts.
The hard part is for someone to actually develop the emulation for all the custom chips in the system. In particular, the two graphics chips are very complex and the documentation is very hard to understand. The same goes for the sound chip. The others are all standard enough to be reasonably straightforward (if not actually easy).
As I think I mentioned that's been another major outcome. I've been working with Yabause developers both to improve their HLE of the CD block, and to implement full low-level emulation using dumped ROMs.
The video's graphic is a bit of an approximation. In practice it appears that every second disc sector is displaced, IIRC. And they've got particular bit patterns written into them to produce a visual logo; these patterns (but not the actual logos) are checked too.
The protection ring is visible to the naked eye for this reason. I can't find a picture, sorry!
I tried to figure out how to reproduce the logo at one point (10+ years ago, when people were less worried about dying drives). IIRC, it's that the EFM patterns used to make the pixels don't make valid Red/Yellow Book sector contents, which causes some weird behavior if you try to read them as such.
You can. That's what traditional modchips do, and there's the Rhea/Phoebe which completely emulates that drive via that interface.
Of course, if you sit at that point in the system you have a different set of problems and capabilities. Much easier to build hardware for, but no data output, and of course you need to disassemble the console to get there in the first place.
The hard part is for someone to actually develop the emulation for all the custom chips in the system. In particular, the two graphics chips are very complex and the documentation is very hard to understand. The same goes for the sound chip. The others are all standard enough to be reasonably straightforward (if not actually easy).