Inside of a submersible warship really is not the place to be conducting assembly of sensitive electronics, and just because you call it "fast automated" doesn't mean it's either of those enough to be feasible in combat situations.

As an example loitering munition with foldable wings is already fairly compact. 2x storage space savings might not justify assembly space and effort

That's fine, it's just the wrong nomenclature.

Lots of weapon systems already require some assembly before use (for compact storage and other reasons), but we don't call that "production" of weapons.