See here.
The platformio file has two configurations, ttgo-t-watch and ttgo-t-watch-macos. You can choose which configuration is used by selecting it in the bottom bar of VS Code (towards env:...).
This is due to the different naming of the device that the watch gets recognized as ( /dev/ttyUSB0 for Linux, /dev/tty.usbserial-... on Mac). So to use it on the Mac, set the environment variable PLATFORMIO_UPLOAD_PORT to your device port, for example as follows:
launchctl setenv PLATFORMIO_UPLOAD_PORT /dev/tty.usbserial-0233D4FC
To make Visual Studio know about this when running MacOS, create a file environment.plist in ~/Library/LaunchAgents/ Documentation on how these environment variables work