Staff to Student Messaging

I've been reflecting on ways of restricting private chatting in Teams an education environment and would like to share my conclusions:

Ideally, we'd like to have the ability to selectively disable private student-to-student chats, while maintaining the ability to initiate student-to-teacher chat.

• What is often advertised as a solution is Scoped Directory Search (which is quite tricky to configure for a layman anyways), which, however, limits chatting only to within a group (so no solution to the problem at hand). 
• Afaik, Information Barrier Policies indeed seem to be able to do the job (but mind you, it's not a simple toggle either), but require licenses ( Microsoft 365 E5,Office 365 E5,Office 365 Advanced Compliance or Microsoft 365 E5 Information Protection and Compliance) that seem like an overkill for adding a single feature to an edu environment.

What's left is to approach the issue pedagogically and technically:

• Prevention: I'm about to have a closer look at Data Loss Prevention Policies and Supervision in the Security & Compliance Center to filter out offensive and abusive language.
• If someone affiliated with the institution (including parents) learns of a violation against the school's code of conduct, an internal pedagogical (approaching those who violated the code) as well as technical (Content Search/eDiscovery in the Security & Compliance Center) process needs to be triggered. (It might be best to have some of that content as evidence.)
• As a consequence, private chatting could be disabled for single students or a whole team by way of creating and assigning a corresponding messaging policy in the Teams Admin Center. This would of course also eliminate the ability for students to get in touch with teachers (and vice versa). Resorting to e-mail would seem like a big step back.

So, all in all, it's a real shame that there is no private chat moderation and/or limitation in Teams as it would be appropriate for an edu environment. I'd already be happy with a policy, but what would be even better is some kind of classroom managment module within Teams in which features like these can be disabled/re-enabled on demand (as virtually all classroom managment solutions can do).

I would have created a Uservoice, but those already in existence don't seem to draw any attention to it.

Maybe someone stumbles on this post googling (binging) the issue and can recommend other approaches.

Best wishes

Neven