This is great, and the direction Firefox should focus on: creating user-first features that other browsers won't and extension authors can't.

I only wish it was more automated. Every site should automatically get its own container.

How much of the anti-tracking value is defeated by non-cookie browser fingerprinting?

I isolate containers by the type of account I am using on there.

So FB gets a different container. Google accounts get a container each. When I need to log in with Google - use the Google account's container.

Work gets different ones - depending on nature of work.

That makes it easy to manage containers for me.

In theory that account's data tracking to an extent is limited. But with browser fingerprinting I doubt this whole set up is very useful once you start aggregating data from multiple providers.

Use the Temporary Containers extension, it does just that.