A PWA has lots and lots of issues regarding trackability. start_url is just a very minor part of that. An application that is actually a weird website will be a

A PWA has lots and lots of issues regarding trackability. start_url is just a very minor part of that. An application that is actually a weird website will be able to track you, there will be Javascript with tons and tons of attack surface for this. If you don't want tracking, use proper local applications and deny them network access.