I think it wouldn't be hard to provide a virtual machine image that provides similar functionality to Google Apps (at least e-mail, storage, calendaring, and address books). Educational institutes switch to GAFE because it cuts away a lot of sysadmin salaries. You do not have to worry about getting your SMTP server whitelisted when a student/employee falls for phishing, ensure redundancy, scale up the architecture as users have more data, replace malfunctioning servers, etc.
Of course, Google's competition to an open source solution is not really fair. First of all, Google can benefit the economy of scale. Secondly, Google is large enough to assume the cost in trade for future income (get them hooked or locked in). Thirdly, Google can to use the data indefinitely to some extend for their own use (e.g. training models).
An open source solution can only win over GAFE (or perhaps Office 365) when a principled choice is made to protect the privacy of students and employees.
tl;dr: it is hard to compete with free.
GAFE requires a dns change, and optionally syncing your directory with them, and has a modern interface for the admin user. So to be easier I'd probably want a debian package, or a virtual machine image.
If someone would package a virtual machine image that interfaced with common directories, provided web office tools, and a version of Classroom (which doesn't have many features), for free, it would probably have some traction, not needing to rely on the internet connection at school to be stable.