Commercial satellite images? With somewhere between 30cm and 100cm resolution? Looking for the letter 'Z' painted on a sidewall of the vehicle?

Rough.

Medium altitude aerial drone imagery would do it, though - just a matter of building something so cheap & plentiful that it's not worthwhile to shoot down.

Who knows, maybe we've given Ukraine the keys to the castle and they're getting a steady stream of 10cm imagery from the NRO.