How does it work?
The idea is simple, we use a really cheap micro controller and a fancy button (from an arcade mashine) and simulate an USB keyboard. This simulated Keyboard doesn't need any special software driver because all operating systems automatically have drivers included and can use it.
When the button is pressed it will signal the operating system: "there was a button pressed".
Which button to use, can be configured inside this micro controller code.
Another software tool (e.g. Automator) is used to detect a button-press similar to a user pressing a special hot key and triggers a script which finally starts the Zoom client.
More details you'll find on the Github page.