Bringing this back to the EU trade deal - one of its more brilliant provisions was having the Europeans buy more American hardware. If they don't want to fund their own defense they can directly pay us to do it.

One of it's more useless "provisions" was having the European Commission handwave towards buying more American hardware, even though they made no formal commitment to do so and would have no authority to make such a commitment anyway, as military purchases are a decision made by country states and not by the EU:

politico.eu - Donald trump defense win europe no arms deal ursula von der leyen weapons defense

But it's brilliant in terms of its political benefit to Trump, who benefits from his supporters believing that this means that the Europeans will buy more US hardware (even though that's not the case).

In fact, as noted in that article, it's probably the opposite that's going to happen. Since Trump has been telling Europe that the U.S. is no longer interested in providing as much of their defense umbrella, all those country states are now prioritizing domestic military purchases. They're beefing up their defense spending, and if the U.S. is now going to be an inconstant partner they don't want that extra defense spending going to us. So they're prioritizing expanding their domestic military manufacturing capacity - the thing that you've said they weren't going to consider doing.