First, police officers conducting a search do not need to present a warrant; they can certainly ask for you to volunteer access. Companies that require law enforcement to provide a warrant may be obligated to do so by some kind of data protection legislation, but I doubt this is generally the case; more likely, we would consider this a courtesy to their customers.

Finally Cellebrite does not seem to actually do any unlocking; rather, it sells it's tool to the government. As long as that sale is legal, they are out of the picture.