Unironically the single-greatest advantage of Firefox over other browsers right now. This should honestly be adopted in the main browser and replicated by others, but for now you should just add this extension yourself.

Finally, synced container is available.

This feature has become an absolute must for my current workflow at work. I keep my personal and work related Google accounts separate. I can isolate certain web sessions from each other for different testing purposes easily. It's just an amazing feature allaround. Don't browse without it!

It is perfect now that it supports sync!

This is THE reason to use firefox. Please develop this extension further