• I'm using FitoTrack to keep track of running, biking, hiking and walking with GPS-data.
• I have a Xiaomi Mi Band 7 that's set up with Gadgetbridge to keep track of especially heart rate and roughly sleep habits (though not very accurate).
• I use Loop Habit Tracker for various habits I want to keep, not only related to health.
• openScale to keep track of weight data with my Xiaomi Mi Body Composition Scale 2. I think this can use GadgetBridge as well, but openScale works like I want, so I have not bothered trying it out.

For the most part, I try to set up automatic data exports from these apps that is synced with my Nextcloud server, and my plan is to eventually develop something of a dashboard that allows me to easily view historical data from all these sources, but as of now it more a backup solution.