The signing into an account in chrome is the killer feature for me. I have work and a couple of personal accounts that I have signed in in different browser windows. That allows me to keep things separate (extensions, mail, browsing, bookmarks, etc).

How do FF users do this?

FF just came out with multi account containers about a month ago ->

https://addons.mozilla.org/en-US/firefox/addon/multi-account...

Do they sync?

What do you mean by that?

If your use case is not covered, you surely can write a WebExtension to provide the functionality. Containers as well as sync are exposed in the API.

I just wanted to know if the containers will be automatically synced across devices.

I can't even get them to persist after restarting FF. :/

Please describe the behaviour you're seeing vs. expecting. Is the session not restoring the URLs in the right container? That sounds like a bug to me. The container names (if you change from default) should be stored in the settings – if not, something is wrong on your machine. If you want to always open some specific URLs on start, pin those tabs.

I updated the container names, colors, and icons. Opened a few tabs here and there. Installed a user agent switching plugin. Restarted to enable said plugin. While the session was restored, including the containers, the non-default container names/meta info were not. Tabs in non-default containers showed up with no labels, and there was no apparent way to open up a new tab in one of the custom containers.

Also, changing a container's color does not change the color shown on existing tabs.