When I research for a project (or even shop for shoes), I often have dozens of tabs open. If I want to share them with others, I have to manually copy and past all of them.
Instead, tab groups could be shared as one entity. An entity that perhaps lives in the Firefox account and can be exported as a unique URL.
Here is a description of a similar concept: https://rybakov.com/blog/open_tabs_are_cognitive_spaces/