Correction: The US was pushing NATO to invest more in US gear.

That was the hope but nothing stopped the EU from making their own stuff.

Nothing, only the gentle hand of US influence over their internal affairs, and the typical nationalistic bickering among themselves.

Those are impediments for sure, but they are not blockers, and if they had the will, they would have overcome that. Most, probably all NATO countries do have their own military industrial complex of some sort and the US is buying from them. Although, it certainly is the case that the US is the largest supplier of military equipment and so, yes, the US would benefit most from efforts to increase military spending.

I agree, the will was never there.

We will see whether the new realities of the war in Ukraine and Trump's approach to Europe will substantially change that.

The whole economic and societal tensions in the west make things tougher...

This is not true, since the 1990 the us was strongly opposed on the eu building or relying more on own defense industry and more closely aligned defence policy, even threatening end of NATO. Lookup the "three Ds" articulated later by Secretary of State Madeleine Albright: No Duplication of NATO assets, No Decoupling of European security from the US, and No Discrimination against NATO members who were not in the EU.

That's because they have more to gain from that.