The last time I looked at containers I think it was an add-on, but I don't think (and please correct me if I'm wrong), it filtered or made active the current viewable tabs.

In Opera there's an icon list on the left and depending on which one is selected those are the only tabs displayed, and/or made active. I'll take another look at FF containers.

Someone mentioned 'about:profiles' above, I think that may be closer to what I'm looking for, maybe that combined with containers can reduce my foot print to just Firefox, thanks for the suggestion