> You can't edit a container's site list, you can only add the currently loaded FQDN to it. So, you can't for example assign *.google.com to your Google container, you can only add each individual subdomain, and only after loading it.

The Containerise addon lets you do both, thoug it hasn't been updated in a few years: https://addons.mozilla.org/en-US/firefox/addon/containerise/