Hopefully wikipedia recognizes this as the official Canary in the Chrome mine. I was first impressed with chrome book because of seeing them used for education, getting my own laptop during school would've been mindblowing to kid me. I was unimpressed with the strangulation process of the OS but again shocked when they added a linux boot mode. There needs to be better alternatives by now, I would be ok with an OS developed by the department of education in conjunction with higher educational institutions. Could have a decent non-profit approach to a browser and ad blockers could legitimately be built in as a "protect the children" aim of approach.
I take it you've never been involved in such an endeavor? What you propose would take a decade a minimum due to the sheer number of nested advisory committees that would be required for those groups to interface. Better a non-profit group begins the work and then solicits these group's input at the design stage.