I was under the impression that ALL websites are basically a kind of webapp. Some (like Lazada) are what you’d call ‘Progressive Web Applications’.
I use Webapp-Manager on Linux, which will set up a shortcut to launch any website/url as a Webapp… at the time of creation, you can choose Firefox or some other browser as the backend (works well for sites that dont work in Firefox).
So for me, the BBC Radio website is a webapp, Overseerr and Sonarr are webapps too.