I am replacing my Bose HU with a Pioneer avh-p4400bh and was wondering if my oem satellite radio unit be compatible with it?

 

No, but with some splicing, the antenna might be re-usable with the pioneer satellite receiver. Nobody's ever tried it to my knowledge, but an antenna designed to receive certain frequencies is pretty much the same, regardless of brand, so long as there's no amplifying circuit (which our satellite antenna does not have).