Good news is that I got the game back working again. It was a simple case of not having updated the assets. However then I was greeted with a vertically mirrored game. Everything was upside down, but left and right seem to be working correctly.
I guess it’s just a coordinate system issue. Negated some stuff to see if that fixed it, but the software renderer is also not something I will use for the Xbox of course. So right now I mostly fixed it, but there are some small issues still. I don’t really care for now.
The performance is also not great, but at the same time not that bad. The best thing is that the resolution independent rendering seems to work. As the game could render in 720p and 1080p just fine. The textures didn’t get tiny, it was all just like on the PC. But the SIMD instructions also just work straight out of the box! Which is very nice to not have to do anything special there for modern consoles.