Interesting thought.
I tend to think that is still literal . . . though I also think it is likely demonic forces/fallen angel forces or some such . . . though there is the highway thing.
It’s just that the logistics of 200 million strong force on land becomes more or less insurmountable apart from UFO transport etc.
I have wondered if the 200 million might be a description of the FIRE POWER of the army. But mostly, I don’t think so. I tend to apply literal interpretations wherever remotely possible.
IF one takes 200,000,000 as the total size, including quartermasters, cooks, occupying/security forces, MP's, and the whole logistical "tail" it becomes much more reasonable: i.e., IIRC, I once read in liner notes to an Avalon Hill game (*)that in WW II, only 10% of the U.S. troops were fighting, the rest were support personnel.
(*) ...or was it in Time-Life's series of books on World War 2?
Cheers!