I had similar complaints about the UX for the built-in containers extension, so as a labor of love, I wrote a helper extension to make containers a little more intuitive:

https://addons.mozilla.org/addon/containers-helper

The simplest improvement is that you can use e.g. Alt+Shift+D to open a little popup and start typing to find your container(s).

You can also use the extension to import and export containers, as well as some other features.

The extension respects your privacy completely and is not programmed to make any outbound network requests.