You can sync Garmin (many devices) health tracker data locally via USB cable or wireless receiver, then parse/graph with OSS scripts:

Code: https://github.com/tcgoetz/GarminDB & https://github.com/mrihtar/Garmin-FIT

Wireless receiver: https://buy.garmin.com/en-US/US/p/10997 & https://www.thisisant.com/