Have the ability to have multiple Microsoft Teams applications open
Having the ability to have multiple Microsoft Teams instances (of the actual app) open would be good. For example, in one instance of Teams, you could be in one tab of a Teams channel, and in the other instance, you could be in another tab of the same Teams channel.
Essentially, being able to navigate through Teams at different places at the same time would be very useful. It's like using the "New Window" functionality within Microsoft Excel / Microsoft Word.