You have options to unlock phones without having the password with Cellbrite.

Not my area of expertise, but the typical use case given in the Signal blog post supposes an "unlocked device in your hands" --

> ...One way to think about Cellebrite’s products is that if someone is physically holding your unlocked device in their hands, they could open whatever apps they would like and take screenshots of everything in them to save and go over later. Cellebrite essentially automates that process for someone holding your device in their hands.

It's very carefully worded ("One way...") to not exclude unlocking without password, though. Perhaps Cellebrite also has password guessing capability?

Historically, Cellebrite devices included exploit code that could unlock most types of phone.[1] I don't know how well modern versions of iOS and Android are supported in that regard.

[1] https://www.wired.com/story/cellebrite-ufed-ios-12-iphone-ha...