The high school my kids went to (they are in college now)
required them to have a phone. They used the camera for projects (videos and photo projects), were told to use the calendar for tracking tests and assignments), and used email and some other app that I don't recall the name of that let the teacher broadcast to the kids and the kids could reply privately to the teacher.
A homework assignment would be on the whiteboard and instead of having the kids copy it down, they would tell them to take a photo of it. They used the browser often for the all kinds of things.
If a kid couldn't afford phone service they could use an inexpensive or second-hand device on the school's wifi. Apparently it was never a problem though - everybody had a phone.
By the end of high school, the kids are 17 or 18 years old - adults. Teaching them to use their phones responsibly isn't a bad thing.