I belive in newer versions they have switched to JS and C#

Gnome-Software and GDebi can do exactly that for you. Download a deb, right click “open with X”, and they’ll install it for you using GUI. You can even change file associations so debs are opened by gdebi/gnome-software by simple double-clicking.

As a read-only SO user - thank you for your answers!

Fourth panel as well, with those bots collecting data for AI training that don’t respect your robots.txt, change user agents and overload your servers