Here’s the timer app I showed at the speakers’ meeting:
Fin - A Timer for Performers par Joseph Cieplinski
https://appsto.re/ca/ilssR.i
I just realized that Keynote on iPad / iPhone can act as a remote for Keynote on Mac. That means you can use it as a second screen to show your speaker notes, even if you mirror your main screen because you’re doing demos.
Since my talk is heavy in demos, I’m going to try that to be a bit more “on-script”…