Currently when a set in ranked finishes your only options are to return to the main menu, but it would be great if we could use emotes, even if limited to have some communication after sets.

I think this is important for community building. It feels wrong to have a great set and not be able to say “Good game” or “I’ll get you next time!”. Conversely if the set was not favorable a “Sorry” or some form of expressing sympathy always feels appropriate.
For me this could be as simple as selecting a chat emote on the final victory screen which reuses the existing UI element that is on character select.

Some grumps always seem to manage how to find using emotes so that they feel salty or toxic. But a 1-button “GG” is really nice to acknowledge your opponent, and feel acknowledged too. And if that’s the only option, it can’t ever be negative, only neutral.