I'd love to be able to specify containers on bookmarks. That's the biggest missing feature for me still.
You can right-click and open in a specific container tab but I dislike the extra step, bookmarks really should be able to be set for a specific container.
Reading through the comments here someone said:
> There are some good add-ons to pin bookmarks to specific containers, which helps.
Might have to go hunting for that but IMHO this should be a built-in feature!
That sounds like a nice hello world Firefox extension project. Why not give it a try?