How to list groups + users that can see this forum (widget)?

[greyteapot]

Goal:
Below a forum/category I would like to display all groups and individual users that are privileged to see this forum/category. In best case this would be a widget, so it would then be easy for example to reveal this information based on privileges to moderators only.

In communities with a lot of forums/categories, groups, and different privileges, this would especially help Admins, Mods or other community managing groups to keep an overview of who has access to which content.

Does anyone happen to have a solution for this?

[greyteapot]

Here a mockup how it could look like on nodebb.org forum:

List unfold: