[kickofline]

I work in a school IT department. We have full Wi-Fi coverage of all our buildings. We definitely have filtering in place, both DNS and managed extensions on student Chromebooks. We use Cisco Meraki switches and APs for connectivity, with Cisco Umbrella for DNS filtering.

The Federal Government has programs like E-Rate that reimbursee districts for up to 90% of the cost of getting internet access for students, but like other commenters have said, paperwork. Unless you can get full support from the superintendent/board, bureaucracy will 100% be your biggest obstacle.