There was some discussion between Purism folks and a UBPorts dev in one of the Matrix channels yesterday, and the impression I got was that the hardware differences between devkit and real Librem 5 should not introduce many headaches. Purism staff developed using devkits, too, after all.
My reading of the conversation was that the UBPorts dev was pleased to hear how similar things were, and believed there would not need to be many changes.