What are you trying to do? The Room Lighting activator device should be usable as a switch (or dimmer or bulb, etc.) device without specific support from any app. If it's looking very specifically for the Group driver of old, then no, but there's probably another way to do it with whatever app.
The internal Button Controller App also doesn’t seem to have Lighting App Groups.
‘As a User I want to turn off all my lighting groups with a single switch’
I create a lighting app groups with all my light bulbs and a few outlets.
Now I want to assign a button in the button controller app to a Lutron pick..
When I add a new action, select control switch and button, the lighting groups don’t show up in the list of devices.
I get that I can do that by assigning a switch to the lighting group but that makes it super messy to manage as now my 5 button pico is spread over a bunch a screens where it was super easy to manage on a single screen with the abc controller app. So no I don’t want that kind of a mess.
Is there another way to work with groups in the lighting app that I am missing? Seems deprecating the groups and scenes hasn’t made things easier… maybe just bring the groups and scenes back?
You simply control the Activator device. You gave that a name in Room Lights (lower right on main page). That's a device you can use in any other automation. This is exactly the way you would control a Group-2.1, by controlling its activator device that it created.