Since Blender 4.2 this add-on is hosted on blender extensions platform:

Use version from Blender Market for older versions of Blender 

It creates grouping-like workflow using regular instances.

Ctrl+G - make Instance (group) from selected objects

F9 (adjust last operation) to set center of the group and set a name

Tab - Opens group edit mode

Deselect everything and press Tab - Return to scene.

Ctrl+Alt+G - ungroup

Ctrl+Shift+G - advanced options like make single user, and change instance.

This add-on uses regular Blender instances, so you can work with "groups" made by this add-on, even if you haven't this add-on. 

Version 0.2:

- Ungrouping (Ctrl+Alt+G)

- Group menu (Ctrl+Shift+G)

- Make single user

- Make existing instances editable in Library

Version 0.3:

- Edit keymap in add-on preferences

- Add / remove from instance