You can use wearable tech to guess those things, but specifically for the stuff you're talking about, companies got so good at actually measuring it, that nobody is really interested in not very accurate guesses, and that market never developed much for cycling. So (as far as I know) there's nothing wearable that can tell you more about bike watts than Strava, which is free. There's a thriving market for wearable running watt meters, but that's because they don't have a better option.

I don't know what your spin setup is. Common recommendation would be to use an outdoor bike on a smart trainer, and then your phone can collect the watt data.