If you were on the wrong platform you had a hell of a time submitting assignments. (CS students on Windows found their C programs would run fine on their laptops but would crash in the CS environment because of compiler and C std lib differences. Engineering students on Linux found that they couldn't open the .docx files to submit lab reports without destroying the mandatory formatting in the tables.)
[0] By "they" I mean the persons who created the documents, not the ones who try to edit them using Gnu/Linux...
Often when people talk about open source "not being as good" what they really mean is "not being the exact same" if a button is in a different spot or something is named differently that is perceived as being "worse" because for the most part people hate change.
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.
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.
Society is living with compromises. If you want everyone to switch to open source software make it better than the alternatives, they won't switch because of any other reason.