Walkie Talkie
How come my walkie talkie won’t connect to any of my friends?
Apple Watch
Use Walkie-Talkie on your Apple Watch
https://support.apple.com/en-us/HT208917
ASC - Late 2012 Mac mini, macOS 10.14.5; Watch, series 3 cellular, watchOS 5.2.1; iPad Air 2 & iPhone 8+, iOS 12.3.2; TV 4th Gen, tvOS 12.3; HomePods, audioOS 12.3 and Airport Express w/ Airplay 2