It is monetized the same way as Firefox, the address bar by default goes to Google search which is really well monetized.

Oh tons of ways. The fact that the default search engine is Google is the obvious one, but GSuite is huge for Google - they're competing directly with Dropbox, O365, etc. and GSuite heavily integrates with Chrome.

ChromeOS of course puts them in the OS market, and it's doing very well for a niche operating system - my entire company runs on ChromeOS in fact.