Yea a browser is required and is provided by whatever browser was used to install the app. So if you “install” the PWA with Chrome, then Chrome is used to open it. On Mac/Safari 17+, it looks like it’s provided by Web App.app, which is probably just a wrapper for Safari. A separate browser install is not required.
It works in Firefox, not sure why Wikipedia has that wrong.
https://en.m.wikipedia.org/wiki/Progressive_web_app