Discord-like plugin for study group

A group on my site is asking for a "study group" space where they can interact as they like.

I've tinkered with some ideas and come up with a few (bad) prototypes on our staging environment using as many of the OOTB widgets as possible.  Needless to say, none fit the bill.

I'm a member of a Discord or two for non-work things and thought the features therein might be a good working idea.  But because this is a "company" community, we don't want data (especially potentially private information) strewn all over different properties.

Doe anyone have a similar scenario and what are you using to keep everything on the platform... OR what are you integrating with that works well enough that you're pleased with the data and security boundaries?