Yes, this is not a PWA system but an SSB implementation. In the context of this thread it’s fine since Lemmy is useless without Internet connection, so why bother with persistent local storage and not just rely on browser cache?
On Linux you can create a simple .desktop file and place it where your system can load it. It will be automatically placed in places where your other application’s desktop files are shown. On Windows you can create a shortcut and change the shortcut’s icon and place the shortcut file wherever you want.
I use this technique on my private Linux machines as well as on my work laptop (Windows 10).