Your first point, there is 100% no way the US is going to “provide AD cover” in a conflict they aren’t in,
To repeat the obvious, they are more than entitled to protected their own assets from attack when flying in international airspace - as the RAF are already doing.
The only thing that would change is the means of doing so.
https://www.itamilradar.com/2022/10/...d-by-typhoons/
Typhoons is are now regularly seen on patrol over the Black Sea when RAF ISR flights are in the area.