I don't know if I would trust that, though.
Google's authorized repair centers have diagnostic tools and software that allows very deep access to the phone. Something that a random maintenance mode wouldn't hide.
When you take your Pixel in for repair, they force you to factory reset it, because they take privacy serious. They don't want anyone to have access to your data through their repair tools.
I'd actually be very skeptical about this if I had a Samsung device. Is there proof that this mode cannot be accessed by their repair tools?