Personally, I find that this [0] doesn't break many sites at all, but messes with cookies to an appreciable extent. Combine this to an extensive use of that [1] and clearing your cache and cookies every day, and I think you're in decent shape while some heavy and heavily lobbied government body inches towards doing something about it.
I went a step further and installed Temporary Containers. Unless the domain is a special one (and goes in a long-lived container), a new tab cannot share any content with other tabs. Whenever the tab is closed all site-related content is removed.
It's still a bit wonky because some sites do redirections, and it's not properly caught (unless there's some option I missed)
The next step is to disable _all_ cookies, even first-party, by default (unless I have a special relationship with the domain of course). It's working surprisingly well and I believe this should be the default.
I did this too. Another pain point I've found is when logging into websites with github or other oauth provider requires grouping that website in with the services perminent container.
It's still a bit wonky because some sites do redirections, and it's not properly caught (unless there's some option I missed)
The next step is to disable _all_ cookies, even first-party, by default (unless I have a special relationship with the domain of course). It's working surprisingly well and I believe this should be the default.