I don't doubt that someone would probably not attempt this or if they did not bother to tell anyone unless they have some remarkable breakthrough, but I remember hearing the same things like this about N64 emulation once upon a time for the PSP too.
Yeah there was a Wip emulator for N64 for the PSP Daedalus, however it didn't run games any faster than 8 - 10 FPS and had no sound, I imagine emulating the DC would be way slower since the DC has much better hardware specs than the PSP.
Heck even the most advanced SNES emulator for PSP Snes9x or something didn't run games at full speed and lagged, same with the Gameboy Advance emulator for PSP.
While DC emulation on PSP might be possible, it isn't practical considering the size of the games and also that it would be extremely slow when compared to running a DC emulator on the PC.
Even PC's which are much better hardware wise for emulation can barely run DC games at full speed, NullDC is sure a wonder but even that struggles playing some DC games and lags even on a decent system.