Python to display name of object/collection in the body of the text

Hi each and everyone!

I propose 30 euros to improve the user-experience on this project:

A script should be added in the ‘’ text file contained in the .blend file.

-The objective is to display the name of the last selected object or collection in the body of a text object (empty by default).

-This Empty text object must keep the same position on the screen, as an overlay would.
(The script already contains the code to make the object face the viewport.)

-A macro of two actions should be linked to the down arrow shortcut:

-Finally, the selection of a parent in the outliner should automatically select all its children

This would allow me to hide all these group labels, while keeping the possibility to select different stages of the hierarchy with all the children.