One of them have been demonstrated for a long time, but it is finally coming to a client near you: Custom Backgrounds is supposed to be rolling out mid April.
I am guessing this has been one of the most requested features at user voice, and with the WFH situation many of us are in, this is most welcome in order to "hide" distractions in the back. And no, that's not my living-room you see in the picture.
The other two features are also most welcome, and will increase the meeting experience for users.
Meet now" button in channels, it will be easier than ever to launch an ad-hoc channel meeting. And by changing/enhancing the landing page for a Teams meeting invitation a user is taken to upon clicking an invite, it is more clear to the end user what options the users have to join the meeting.
There are no admin controls related to these feature at the time, but you may want to update your training and inform your users about the new features.