Hi SERMONISDiana-1174,
You can use keyboard shortcut to toggle mute (Ctrl + Shift + M) now.
The feature “Push-to-talk voice communications” is still in development. You can monitor the progress by this Microsoft 365 roadmap:
https://www.microsoft.com/en-us/microsoft-365/roadmap?filters=Rolling%20out%2CLaunched%2CIn%20development&searchterms=push%2Cto%2Ctalk.