So...there are profiles (about:profiles) and you can run them in parallel. But it's not really feature meant for consumers as it is in Chrome.

Multiple profiles in parallel? Sure, you can start multiple instances of Firefox in parallel from the command line and use them with different profiles. I do that (on a Mac) regularly. Works under Windows too, IIRC.

You don’t need to use command line options to open new profiles in Firefox. Just open the about:profiles page.

Yes, Firefox supports multiple profiles in parallel. For a Chrome-like user interface, try the Profile Switcher for Firefox add-on:

- Add-on: https://addons.mozilla.org/en-US/firefox/addon/profile-switc...

- Source: https://github.com/null-dev/firefox-profile-switcher

I know they have containers but maybe I’m using wrong as it’s cumbersome.

you have containers that are better that parallel profiles

A few months ago I tried to go back to Firefox and used containers a lot. It works fine, but sometimes I'd pick the wrong container, defeating the point of using containers (eg: using Google Search for personal stuff while logged in to a work Google Account).

Containers are useful and we can do interesting things with them (eg: temporary containers), but they don't replace profiles. With a profile I don't have to mix personal bookmarks with work bookmarks, I can use different extensions/settings, a different theme so I don't use the wrong profile by mistake, etc.

Yes. But launching them isn't as easy as in chrome. Depending on what you are using them for, firefox containers might be sufficient.