Passkey is some sort of specific unique key to a device allowing to use a pin on a device instead of the password. But which won’t work on another device.
Now I don’t know if that key can be stolen or not, or if it’s really more secure or not, as people have really unsecure pins.
Good luck in court
https://www.computerworld.com/article/2743684/mich--state-police-confiscate-cell-data-at-traffic-stops--won-t-say-when-or-why.html
https://www.vice.com/en/article/aekqkj/us-state-police-have-spent-millions-on-israeli-phone-cracking-tech-cellebrite
They even brag about it
https://cellebrite.com/en/kansas-investigators-use-advanced-analytics-to-speed-their-work-and-reduce-violent-crime/
https://m.slashdot.org/story/418156
Make sure your devices are up to date
You link to articles about law enforcement hacking phones to get data as a reason not to use biometrics? If they are hacking your device it doesn’t matter if you use a password or a fingerprint.