As it has been said multiple times PSP has low level GPU access possible and that helps N64 emulation tremendously (and PSX too for that matter). Sony published that information to the licensed devs to get most out of the machine, and that information has been leaked to, or has been reverse engineered by homebrew people, so it can be used in projects like Daedalus.
Meanwhile Pandora's GPU can only be accessed through GLES, and this is not that good for emulation of other GPUs. Following desktop graphics traditions it's maker, ImgTec, is not publishing low level information because it thinks it's their trade secret and revealing this will benefit their competitors.
Porting daedalusx64 as-is to pandora (or any other ARM device) is not possible not only because of MIPS code, but also because pandora doesn't have PSP's GPU. If you replace the MIPS code with ARM and PSP GPU code with GLES, it's unlikely you'll get anything better than Mupen64plus.