Now that Containers is available on AMO, the Containers collection should be added to the Firefox Privacy Add-ons section. (Particularly, Multi-Account Containers and Containers on the Go)
AMO page not found, containers options are into the browser:
[SETTING-56+] Options>Privacy & Security>Tabs>Enable Container Tabs
[SETTING-ESR] Options>Privacy>Container Tabs>Enable Container Tabs
Oops, the collection went away. Here's the link straight to the add-on on AMO: https://addons.mozilla.org/en-US/firefox/addon/multi-account-containers/
I think this depends on https://github.com/privacytoolsIO/privacytools.io/issues/1327
Perhaps consider Temporary Containers [1][2]. Firefox only, like multi-account-containers.
Listed on ghacks user.js extension list [3].
[1] https://github.com/stoically/temporary-containers
[2] https://addons.mozilla.org/en-US/firefox/addon/temporary-containers/
[3] https://github.com/ghacksuserjs/ghacks-user.js/wiki/4.1-Extensions/44f04f0e2c32d88b3ce8b3f1e78ba6d42b2a9742
Just wanted to mention that Temporary Containers is a viable alternative (or complement, if you use permanent containers as well) to Cookie AutoDelete, since almost all storage and cache is covered by containers and hence removed after the tab is closed - while cookie cleaners rely on manual API calls, and as of yet aren't able to clear some of the storage reliably; also they can't isolate cross-tab cookie/storage access.
Disclaimer: I'm the author - feel free to ask if there are any questions.
I don't think containers are useful if the user has others extensions properly configured (uBlock Origin and uMatrix). Let's not fall into marketing traps and encourage users to bloat their browsers with add-ons.
Edit: also, installing many add-ons increases the effectiveness of fingerprinting.
uBlock Origin / uMatrix aren't Data-Cleaners - without dedicated Data-Cleaners storage is persistent and lets e.g. the same first party domain easily recognize users on repeated visits. More details on that are here: https://github.com/stoically/temporary-containers/wiki/Comparison
Add-ons can increase fingerprinting, correct. Containers however don't really have an detectable surface, since they're basically "profile per tab/container", which isn't detectable in itself.