

Most phones aren’t zeroing out the SSD on factory reset AFAIK, might not even format the partitions.
He was using a Pixel and he fast wiped the phone. That means that he was probably using Graphene OS and entered the duress password when the agents told him to unlock his phone. See: https://grapheneos.org/features#duress




It doesn’t bother with files. The GrapheneOS wipe process deletes (by overwriting with 0s) the encryption headers on the drive and zeros the keys out of memory before shutting down.
You should never, ever allow anyone access to your unlocked phone that you don’t trust. Even an otherwise smartphone could be exploited if it is unlocked because it exposes a much larger attack surface.