Ask HN: Advice on a passion project in a small (but growing) market

Can you not build this as an app for an Apple Watch using NFC tags? Or any other commercial wearable. That'll save you a boatload of money, and probably be more appealing to climbers who usually do other sports as well and would rather have a single device.

When it comes to raising money, investors will want to know how big your moat is. For instance, if in the future Garmin or Apple added a climbing feature to their product, can you keep growing?