I haven’t seen this posted here before. Sorry if it was and my search failed.
A shout-out recommending Intervals (Pro level) for interval training on iOS and Watch. Very customizable – in fact it could be used for activities other than workout training. It announces steps in the interval in advance (configurable) and has a good Watch app.
SECONDED! I love this app. I’ve used it for a long time. For the past few months I’ve been using its couch to 5k program. It handles watch and phone way better than big name apps like Nike Running (which is a partner but sucks at using the hardware).
I activate it on my watch so I get the workout tracking, then I open the app on my phone (which o have sitting on the treadmill shelf thingy) and open the remote view so I can see the info from the watch on my phone screen.
I haven’t thought about using it in other ways, like for pomodoro, but that’s a really great thought.