Plenty of NATO members already build and buy from non-US sources. France basically made it a principle because of their historic fence-sitting NATO policy, Sweden mostly builds its own (but licenses parts from US/UK like fighter engines), other countries are buying artillery or tanks from south korea, etc. The US itself buys anti-tank weapons and riverine patrol boats from sweden, dutch rifles, german handguns and much more.

"but the shiny new weaponry all comes from US contractors" is not true.

It is true that the US has spent far more on it's military and made it far more global than any other country. It is also true that the US acted as a guarantor for west Europes security for most of the last 70 years and that should not be understated. That era seems to have come to an end.