Well, we've already done something similar to this with the Blue Beetle scarab. The only difference is, it's actually ancient Ohm tech, not Daligig, because way back when the Ohm first started traveling the multiverse eons ago, they left both genetic and technological imprints wherever they went, affecting a number of species in different realities.

Perhaps the aliens that "created" the Guyver were descendants of a race that encountered the ancient Ohm, and the Guyver suits themselves are remnants of Ohm technology like the scarabs are. Does that work for you?

(As for Stacy being biological, there's another reason for that which hasn't yet been brought up in-game yet)