@Stewby55 

Perhaps you can get a Tapo hub, an H100 or an H200. It can be an alarm/ringing device when needed, initiate inside the Tapo App. 

If you need to enable communication, consider placing a Tapo smart sensor (Tapo S200B) and a camera near the hub.

1. The owner can set the camera to always be in privacy mode and then create an automation rule for the camera to exit privacy mode when someone presses the button.

2. The camera and hub can be shared with others, granting them limited permissions on Tapo devices. In this case, when the camera is in privacy mode, the invitee cannot see the live stream or disable privacy mode. 
How to share my Tapo Smart Devices with family
How to create Smart Action (automation or a shortcut) of my Tapo devices

As an invitee, you can use ring the hub in the Tapo App. When someone hears the ring and presses the smart button, the camera exits privacy mode, and the invitee can then watch the live stream, initiate one-way or two-way communication.