I'd be all over some sexy PC-FX homebrew!!!
But would you, and the active developers here, really want to write some?
It should be possible to create a USB-based Develo-like system that talks to a retail PC-FX through the 2nd joypad port.
The Saturn guys apparently have a GDB debugger running over the Action Replay Pro's PC comms port ... so the same thing should be possible with the PC-FX through the joypad port.
It should be much easier than the PCE's Develo-board since the PC-FX hardware natively supports output through the joypad port.
That would work on a modern PC and avoid the need for an expensive-and-rare PC-FX GA board.
The GCC work that the Japanese fans did in 2000/2001 was to re-implement V810 support in GCC based upon the existing V850 support.
The main CPU in the PC-FX is the NEC V810, and the V850 is it's big brother that was developed at approximately the same time ... they are about 90% similar (from a compiler's point of view).
The V850 is still sold for the embedded market and is currently supported by GCC ... although I'm not sure that there's much reason to go more recent than GCC 3.4.6 in order to get a solid C99 implementation.
But it's all a significant amount of work to develop and put together ... for a machine that sold less than 200,000 units and had so few games that people care about.
If excitement for PC-FX translations is any indication, you'd certainly garner some healthy interest; and if you made something gaijin friendly and fun, I bet you'd even convice a few guys that they need to buy a PC-FX.
I can certainly see the value in translations that run on the original platform hardware ... that's a work of love and honor for the original creations.
But do enough people really care about new stuff for the PC-FX that they want to drag developer's attention away from PCE homebrew or (sorry to offend you
) Saturn homebrew?