Join Teams work meetings from Microsoft Teams (free) and vice versa

Microsoft Teams (Free) users can currently join Teams for work (or school) meetings only as guests, which requires them to use a browser and results in a sub-optimal experience. The new feature rolling out will allow these users to join Teams for work (or school) meetings in one click, without being redirected to the browser or asked to fill in their name/surname. They will also be able to continue collaborating with the meeting organizer and other participants via meeting chat after the meeting.  The feature will work in the opposite way as well, so Teams for work (or school) will just as easily be able to join meetings hosted by a Teams Free user with one click. This is associated with Roadmap ID: 167326

Audio sharing from a Teams Live meeting

Although sharing of the desktop audio have been available in Microsoft Teams meetings for a while now, the feature has not been implemented for Live events. Until now. As of April, this addition to Live events features should be available to all according to Roadmap Item 63276
Make sure the sharing policy is set to "Entire Screen" or "Single application" for this to work.