That threat or that demand should be easy to fulfil on paper though via bureaucracy – just in case he makes it.

The USA has so many services and authorities included in their military, that other countries usually have separately. E.g. cost guard, army corps of engineers, space force etc.

It would just require some formal budget reallocation for all the countries, that have those services and authorities not in their military budget. And magically, on paper, everyone would suddenly be way over the 2% NATO target. With the USA being in a spot to not even complain about that ‘trickery’, as the mentioned sectors are in their own military budget anyway.