Indeed, the amazing images that we've all seen of the coronavirus are from the same technique, cryo-EM tomography, but the overall size of the specimen is also much smaller. There's a limit to how much data can be processed, resulting in a scale-resolution tradeoff.

Now my info might be outdated since it was a few years ago, but I was once told that when you use one of those microscopes, you bring with you a terabyte hard drive for each specimen.