TreeStyleTabs works out of the box without any sort of hacking around. I really don’t get this mentality. Firefox’s containers have no corresponding feature in chrome, they haven’t copied it and it is a huge win from a privacy PoV.
As for privacy containers - you can easily switch profiles in Vivaldi. It's not integrated to the same degree where you'd get tabs from many profiles in one window, but it works for me. If you like Firefox Containers you should also know that, ironically, unlike Chrome Firefox doesn't have proper site isolation. [0]
[0] https://madaidans-insecurities.github.io/firefox-chromium.ht...