The answer to that is both yes and no.
They can press gang and hoodwink enough of their population to fill 800 tanks after all it is only 3200 people and some of them will have had experience in something with an engine which seems to make them eminently qualified in Russian military eyes hell friends had a 1980 Lada Niva and it performed in almost every way like tank until it fell apart.
So yes they can crew 800 tanks but no they can't crew 800 tanks with qualified and experienced crews so 801 ATGMs pretty much solves the problem, 50% success rate on the missiles and 400 abandoned and broken down tanks thanks to quality Russian vodka fuelled workmanship.
I think this is the most likely point of the explosion, if you look at the first picture in that link at the second pile from the left they look out of alignment, the other four sets of piles look fine, while I suspect a seaborne attack due to the timing of having a fuel train overhead they is also a possibility of it being a sea mine as plenty of those have been set loose in the Black Sea.
One of the reasons I doubt a US supplied USV is that by now the Russians would have recovered parts and blamed the US which indicates they don't have any.