I emailed nemu64 teams lemmy about porting to dreamcast. This is what he told me:

“1. dreamcast would be too slow (unless you super optimize…maybe even more
than corn does)
2. it doesn’t have enough ram to load cartridge + rdram + some dynrec data
(about 10 mb) + emulator + wince
3. if we streamed from the GD-Roms it would be very slow, as n64 cartridges
have high access rates
4. Nemu64 is X86 specific – porting would definately NOT be easy. Had to
write a completely new dynarec.
5. I don’t have a dreamcast”

I guess that means we will not have a port any time soon of nemu anyways. 🙁