Apparently you can create a local account on a chrome device [1], although I can't vouch for the process; otherwise cloud auth is tied to Google, yes. You could use a guest account for everything, if your really want; but then you lose out on persistence.

But as long as you accept that everything you do is in a browser; which is reality for the vast majority of computer users, there's no real lock-in. You can just as easily use the browser version of Microsoft Office as the browser version of Google Docs.

You're certainly locked into Google for the browser and for updates, unless you do a lot of work. But it's been a while since it was common to get commercial OS updates from a 3rd party.

[1] https://www.xda-developers.com/how-use-chromebook-without-go...