Been a minute since you posted, but what the heck? I'll answer.
I lived in apartment for years and my vehicles weren't garaged. For the cowl (the area at the base of the windshield where it takes in air for the cabin), you're going to have to clean it out once in a while. You should anyway, because all sorts of stuff gets in there without you knowing. I suppose you could put something over just that spot, but you'd have to take it off every time you drive, and the wind could take it.
For a decent, battery powered vacuum, I would check the usual places. Amazon, Best Buy, etc., and maybe Home Depot or the like would have something heavier duty. But all you'd really need is something with a hose and some attachments that has decent suction. Otherwise, if you're near a car wash, you can use their vacuums. Expect to pay over $100 for anything battery that works without disappointment. Vacuums aren't cheap these days!