Yeah interesting idea I play football casually (1x per week) and would be curious enough to install an app to see some analytics although attaching the phone somewhere to my person would seem to be somewhat of a barrier of me adopting it. I probably wouldn't pay 50$ for a device, and I wouldn't carry a phone in my pocket or on my arm so im probably not your target audience (maybe if I had an apple watch I would keep it on to get this data).

On a different note I think you should probably ignore or not ask people what they think of your idea or app because their answer is either going to give you false validation (aka someone saying its a good idea has very little to do with whether they would actually use it) or its going to discourage you because others don't share your perspective on why this is a great project. I'm happy to give more specific feedback if you have any questions though! I think the name and domain is 👌 I would also challenge you to think about the core value proposition to your target audience and make it the most prominent text on your homepage 🚀