Usually a general contractor is hired to demolish a building and they will go in and strip it of everything.
I’d find out who is doing the work and try to find the foreman and asking them. They are the ones who will physically be removing the devices and tossing them in the trash or a recycling bin, and they are already being paid by the the district so they usually don’t care if you grab a few devices (as long as you sell yourself as a hobbyist and aren’t trying to grab a bunch of devices for profit).
The facilities manager should know who the general is on the demolition. Try to also find out the schedule from the facilities manager, when they will turn the building over for demo, etc… all the wiring will be ripped out first, so fire alarm is one of the first things to go.