Also it's pretty heavily implied that the BoS is the canon ending for Fallout 4 seeing as the Commonwealth faction is the dominant one and they've clearly been able to produce more Prydwen-type ships, probably with captured Institute technology.

Not that this disproves the BoS Fo4 ending but I don't think the extra Airships weren produced by the Commonwealth chapter, the other chapters (Yosemite, Coronado etc) already had them before the meeting so I think it implies they've had them for a while and that they weren't built by the Commonwealth chapter then distributed to the other chapters they've had limited contact and not the best relations with, since its only been 9 years between Fo4 and the show and each chapter seems like they'd horde any new airships rather than give them to tenuous allies, it's more likely they were built sometime in 200 years post-war when the BoS was more cohesive and at a higher stage of power