Yes, if you want it to. There is a pwa button that appears on pwa supported sites that lets you toggle between app window mode and normal browse tab mode.

Fullscreen will hide the window decorations, but that won’t solve the use case of “behaving like a desktop application”. I use PWAs for websites that are applications (Outlook, Teams, Spotify etc). I want these windows to be dedicated to those applications and nothing else. They should appear in my window list on alt+tab, not be able to navigate away to something else etc.

Similarly, Rubino says web apps in Firefox will not use a minimal browser frame and will continue to show a main toolbar with address bar, extensions, bookmarks

But why, the whole purpose is to behave like a stand alone app.

Death By Snu Snu

Is there a difference in alcohol level? Alcohol evaporates easier than water.