If you mean Firefox containers[0], the closest you'll get is Profiles[1] since Orion is based on WebKit. Its ___location in settings is different from the Safari docs, and that's the only difference in Orion's implementation as far as I can tell. You can't open a tab in a certain profile, instead each profile opens in its own window, which is a lot more cumbersome than Firefox containers.

Arc, another Webkit-based browser, has an interesting implementation combining Profiles and Arc Spaces[2]. Instead of switching between windows, you switch between "Spaces" in the sidebar that are linked to a profile.

[0] https://addons.mozilla.org/firefox/addon/multi-account-conta...

[1] https://support.apple.com/en-us/105100

[2] https://www.youtube.com/watch?v=A5BzkowY_B8

Arc is based on Chromium not WebKit.

My bad, it's based on a fork of WebKit.

Blink forked from WebKit almost 12 years ago, there's so many differences at this point that it doesn't make sense to call it a WebKit fork

I'd agree, at least partially in my case: Container Tabs is a killer feature for me with Firefox. Especially compared with the Temporary Containers extension on automatic mode, basically each new tab is like a fresh browser profile with zero cookies/local-storage.

I might consider demoing Orion on Linux even if it doesn't have container tabs, but at this time I wouldn't consider a full switch without that feature.