What they want is *warrantless" snooping. IOW A fishing trip.
Fact. Withholding information during an ongoing investigation is already a crime.
Fact. Withholding passwords and logins during an ongoing investigation is often a special crime in addition.
So yes the Feds can get access already.
This access is for lazy data fetishists Feds
If you have physical access to the device it's pretty much game over but these Aholes don't want to go out of their offices and do real police work.