I think it would be cool if once you completed your faction or during you'd have access to someone who can unlock faction objects to set in your settlements.

Example let's say if I'm in the instituite I can create gen one synths to do a few of the chores(maybe a limit on that)

Brotherhood could get vertibird pad as well as bunker stuff.

It would look like your chosen faction is truly taking over the capital wasteland. I think it would be cool.

sounds good