[rchaud]

> If I log into YouTube, that requires me to be logged into Google everywhere and I do not want that at all.

You can use Firefox Containers to sandbox Google logins.

Alternatively, you can use a different browser when accessing Google-owned websites.

[TedShiller]

If you click on a YouTube link now will the browser know what container to open that in?

[wasmitnetzen]

Yes, you can configure it in a way that every Youtube link opens in the Youtube container.