This is a feature that I rely on constantly while using Chrome. It helps me stay organized and keeps me from being overwhelmed. It is definitely a quality of life feature that makes a big difference.
Still would very much like this, tab collections aren't the same as I would like them to update as well as I change each tab. As an example, I like to read certain webcomics on my phone, I don't like to have to remember exactly where I was nor do I want 5 tabs constantly taking up space.
Yes now that pull to refresh was added I was soooo hyped. Only to realize I always have 20+ tabs open in 5-6 groups ranging from news, tech, comics, social and what not and this cant be done in FF 😞
Hopefully, Firefox developers will focus more on the Android version, especially tab collecting. This idea has been proposed for a long time, but is not yet available