Crossover is the commercial version of the code behind proton, developed by the same company. It doesn’t work as well on Mac as on Linux. Since “Like Linux but worse” is exactly the point you’re responding to, so you’re pretty much in agreement with them?
It’s not impossible to invade the US. It’s been done several times already, for example 1942 and 1812. Mexico, which shares the same oceanic borders, was invaded by France in 1861 and of course the entirety of the Americas was essentially invaded by colonial settlers.
It’s unlikely for other reasons, but nothing about it is impossible.