“Testimonial”
I can’t see how conveying the information could be determined to be anything other than testimonial.
The password is not testimony; it is a key to unlock a device. Sort of like a key to a wall safe. If a court has issued a search warrant for the wall safe and its contents, pursuant to due process, then the defendant/owner must allow the wall safe to be opened. The contents of the safe are not "testimonial" or in any other way 5th amendment protected from the duly processed warrant.