@OP your link doesn't discuss the 328 unless you scroll down past several articles by the same person.

Actual link to the article glossing over usage of the 328

Found halfway down the linked page:

“An ATmega328 microcontroller, voltage booster, MOSFETs - everything is standard,” says UAV Developer. “What is worth paying attention to - the [Ukrainians] are absolutely right on the path of electrifying ammunition.”