@ghost_letters @TimWardCam @PavelASamsonov
That is a "Progressive Web App" (aka "PWA"). Yes a fair amount of discussion about them elsewhere in the discussion.
Basically they can do many of the things that native apps can do (background running, offline functionality, notification etc.) and can look like a normal app. Difference is that they are actually running in the browser so you don't have the potential privacy and security issues of a native app.