How has Google monetized Chrome?

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.

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