Well, someone could spend the time re-writing FlashFXP in VC++ or VC#. With VC++ you can probably port it to whatever platform you want. With VC#, i THINK MACOS has a .NET FrameWork plugin that will allow for C# programs to run. NOt 100% sure.
But porting Delphi to C is not the easiest thing in the world. Nor is C for that matter.
I love flashfxp, best program under $50 i've ever used.