Would really need to be able to record manual lap times on the wear os app. For now, the app is absolutely useless if you want to do interval training. I was actually surprised that this wasn't a feature, had I known, I would had bought a Garmin watch instead of a Galaxy Watch 5.
It should be quite easy to add? Short press on the back button for lap time, and long press to pause activity.
Overall the wear os app is quite disappointing, I hope this change soon.