There isn't a powershell script I'm aware of, but you can connect with ssh and run pfSsh.php playback changepassword admin, then enter the new password and confirm it. Together with something like clusterssh or tabs with shared input in SecureCRT you could change a bunch to the same password all at once.

The only thing not backed up there would be packages pulled in directly from FreeBSD by specifying a different repo. Those are not directly supported though What did you actually have installed from FreeBSD? Steve

@_neok Yes, old backup works. ;)