First make sure in the site settings RSS isn't disabled.

Then (as a logged in user) when you go to a page that supports RSS (like /blog/all, /activity) in the footer there is a link to the RSS feed.

So after searching some more I found an old plugin named au_subgroups but it seems to be very old and not managed anymore. Sounds like what I need so I may try to update it. I also found a plugin named Profile Manager which seems to almost do what I want but not quite so maybe I need to tweak it a bit also. In any case, thanks for bearing with me and any advice or other solutions great appreciated.

While there's no ready-made plugin, your problem can be solved with a custom plugin.

All you need to do is add a new "Category" field (input/text by default or input/tags for multi-categories) to the group creation form and organize pages with group sorting by category.

au_subgroups

Look at hypeGroups.

(Ismayil recently updated this plugin using AI, so give it a try, it might not work as intended.)

This plugin doesn't contain an interface for creating subgroups from the admin panel, so you'll also need a custom plugin to override the structure of your groups' subtypes.

Readme is very helpful.

Thanks for this will take a look.  Had to abandon the Profile Manager as I couldn't get it to show categories on the Groups page. Always showed the Elgg default group page no matter what I tried. hypeGroups looks interesting though.

Yes we share some variables between frontend and backend.

You could fix it in your theme by also extending the admin.css and changing the font color or background color just for the admin side.