You will probably always need a "fork" because Asahi needs a custom installer and bootloader. It is also probably a good idea to recompile everything for the Apple ARM architecture.
My comment was of course from the perspective of the game developer. For PC/Windows games it has always been the case that you need the required HW to play the game in a "satisfying" performance.
A lot of RT features makes game development faster (or more efficient) so you won't be able to play the game without them.
I really liked the first Virtua Striker. It is pretty limited but can be fun in small doses even today. There is a PS3 port and of course Mame if you want to try it out!
Yes, Lumen (and raytracing in general) has a performance overhead. If you don't want that you can skip that feature. Split Fiction and other games choose to do so.
I think certain games like Robocop are awesome on UE5.