Onenote used to integrate with LMSs from a variety of companies and grades could go into the LMS. Notebooks could be manually added to a specific class after the fact. All of this seems to be removed now (class notebook update at end of November 2020). This is highly frustrating and lowers the utility of onenote unless a school is using teams. If the goal is to entice schools to consider teams it is unlikely to occur from my experience and more likely will lead to them abandoning O365 and moving to google product more extensively than they already do. In my school the IT administrator simply disabled teams even though some groups had already discovered it and begun using it.
Microsoft has been quite good lately about working with other groups and allows other organizations to interface with them, but the changes to OneNote classnotebooks seem to go against this.