Skimming the Github repo, looks like this uses rt64 under the hood for the raytracing support ( https://github.com/rt64/rt64 ), and that uses the ubershader technique to emulate the GPU. This excellent article talks about the what, why, and insanity that are ubershaders: https://dolphin-emu.org/blog/2017/07/30/ubershaders/
Static recompilation from one machine language to one other language is somewhere between extremely difficult to not being generally possible in practice [1]. To make recompiling something like this properly, you need some help from the binaries that make recompilation easier [2] and on top of that you need to patch certain things to make this work [3].
Dynamic recompilation doesn't have this problem. It allows you to create software you can dump the original binaries+assets ("ROMs") in and it will generally emulate it.
There's a lot of confusion about how generic this solution it. It's extremely impressive in how much work it saves making recompilations/"ports" much easier, and it will be very valuable. But it is not able to replace the need for traditional emulators.
[1]: https://cs.stackexchange.com/questions/155511/why-is-static-...
[2]: N64 game binaries may happen to avoid a bunch of things that make general static recompilation hard that help this approach, but I don't actually know.
[3]: The Majora's Mask recompilation repository contains a lot of handcrafted patches to make it work: https://github.com/Mr-Wiseguy/Zelda64Recomp
HOWEVER.. writing an recompiler (not feasible for 8bits due to the amount of self-mod code) you could probably insert pattern checks to detect writes to DMA-starting locations,etc (thinking back to our PS2 games) and transform it to safe sequences without accurate timing for most games that really only would be happy with some extra cycles.
The UK C64 disk for “Skate or Die” had copy protection that did exactly that, as an example.
I think it went through about five iterations.
My crack was to step it with the original disk to decrypt the encrypted part and modify the code to jump over the decryption. It was pretty sophisticated for the day.
To another extreme, Ocean disk games had a “IsGenuineDisk” style function. It returned 1 or 0 in the accumulator. I could crack it in under a minute with a disk sector editor.
Oddly, I ended up doing Mac copy protection years later.