have you tried using multi-account containers? it's perfectly suited for segregating different identities like work/bank/shopping/social/whatever all in the same browser instance. that plus temporary containers for "privateish" windows is awesome. I am not sure why that's not installed by default if it's not as it is really great.
I do use FF containers and its great, But for my use case I found it to consumer more memory as I don't need the websites open all the time and so pinned websites on different browsers were efficient for me.