I haven't taken exact measurements, but any issue with using a fork designed for an integrated headset with a press-in-cup headset like an FSA Orbit X or the like?

Provided the fork crown doesn't protrude beyond the edge, I'm wondering if there are issues with crown race/bearing contamination, or if it will just look awful no matter what.

I've never heard of a fork being designed for an integrated headset. Modern carbon forks are designed with a 50mm crown width to look better with integrated or tapered steerer tubes, but that doesn't preclude their use with an external cup headset. I have a carbon fork with a 50mm crown and external cups on my road bike.

Big factories making a half million bikes can get forks and headtubes matched so they appear to flow one into the other, by making both..

with only a line separating them .. that is the styling integrated headsets make possible.