After much bumping my head against a wall I found the Web Apps program in the Application Launcher (where the Start button is in Windows) > Internet > Web Apps. This let me do the Progressive Web Apps thing you spoke of.

Ooft! This is going to be a long journey for me, eh? XD

Thankyou. Though I do not understand most of what you’ve written. I am very much at the must-be-handheld-through-most-things stage of the Linux journey. Flathub has been a god-send for this very reason.