While far from being perfect, I find it good enough for keeping things separated, especially when using a desktop/workspace workflow. For example, in workspace/desktop 2 I have a Firefox window opened with the first tab set to "container A", so hitting ctrl-t there opens new tabs with the same container "A", so I'm logged-in for all projects A. In another Firefox window in workspace 3 I work with "business project B" tabs (where I'm logged into different atlassian, github, cloud, gmail, ...)
Then with a Window Manager like i3wm or Sway I set keybinds to jump directly to the window (and workspace), using the mark feature [1]
It's also possible to open websites directly in specific containers so it's flexible. For example on my desktop 8 I have all my AI webchats in "wherever my company pay for it" tabs: `firefox --new-window 'ext+container:name=loggedInPersonnal&url=https://chat.mistral.ai' 'ext+container:name=loggedInBusinessA&url=https://chatgpt.com' 'ext+container:name=loggedInBusinessB&url=https://gemini.google.com' 'ext+container:name=loggedInBusinessB&url=https://claude.ai'`
It's also the only way I found to keep opened multiple chat apps (Teams, Slack, Discord, ...). The alternative electron apps are as resource-hungry, and in my experience never handled multiple accounts well (especially Teams).
[O] https://addons.mozilla.org/en-US/firefox/addon/sticky-window...