Not something that we’ve configured ourselves but it should be possible.
You can add multiple Apple Business/School Manager accounts
You can only map one domain to one Apple Business/School Manager account. So long as each school has a separate domain in 365 then that part should work
You would probably want to create some dynamic device groups in Azure Ad so that you could easily say which devices belong to which school
If you are using shared devices then it is a lot simpler and should work quite well
Definitely something which needs to be proven as we’ve not done it ourselves but from what we can see here, it should work.
