Brainiac God was (at least supposed to be) the Silver Age Brainiac after mutating due to his multiverse observations, so he was from Earth-1 Colu (although the planet was inconsistently named at times and Yod was another one of its names), not the rebooted Yod-Colu. The Brainiac from Yod-Colu was just an avatar, yes. Of course, the Computo here is nothing like the Pre-Crisis Computo either, although it's mentioned that it has evolved, so whatever.