The Walkie Talkie app in Teams provides instant push-to-talk (PTT) communication for your team and is now available on Android.
This is a very cool feature that you can test before deploying it as :
Adding Walkie Talkie to your app list:
In the Microsoft Teams admin center, under Teams app > Setup policies, you should have Allow user pinning set to On. Then, under the Pinned Apps section, click +Add Apps.
On the Add pinned apps panel that appears on the right, use the Search textbox to look for Walkie Talkie. When you have it as a search result, select the Add button to the right of the name to add it to your list.
The Walkie Talkie app should now appear on the Pinned Apps list, and be available for use once you click the Save button.
You can create a new App Policy instead of modifying your Global Setup and assign it to whomever you want from you users !
Note that in term of licensing Walkie Talkie app is included in all paid licenses of Teams in Office 365 subscriptions.
For more information : Communicate with your team in Walkie Talkie (microsoft.com)