It's just a bunch of decoded databases from an image of a device, with specialized tools to sort through and relate them to each other. Combine it with OSINT stuff, existing criminal records, evidence and ongoing investigations. Now you can map out wwwwwh with relative certainty.
I doubt the courts could force them to divulge trade secrets as to how, specifically, the tech behind the evidence gathering works. The investigator just has to ensure chain of custody remains intact.
For the record, I'm not saying it's good, but the concept is there and there are many of digital forensics companies doing exactly this. It's literally hacking, but for The Man. And there's a lot of money behind it
Where I used to work, we had a massive digital library of android phones with confirmed exploits. They went up to quite recent phones and OS versions. The android team wasn't particularly big because there wasn't a major need for manpower to keep up. The iPhone team was highly specialized and had their work cut out for them. I wasn't on either team (Windows and sort-of OS X) but I fell into their meetings and wikis quite often due to platform overlaps.
And the latest and greatest wasn't necessarily what was getting attention anyway. Plenty of people worldwide use old phones