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.
The Open Food Facts smooth app is free and open source. It's available both on FDroid and the Playstore, though I personally update my app directly from the github page here.
Like the other commentor- I also tried hard to use wger but it was just too unintuitive. I switched to Liftosaur and love it for making a weight lifting routine easy to design and track:
I did test self hosting it and it's not too bad, but just switched to my iPad and subscribing for the premium because the auto calculating the plates for each lift saves me a lot of time and I feel good supporting this developer.
I use Track & Graph from F-Droid for tracking the amount of workouts and my weight. It's not really specific to fitness or health, but I use for its support for exporting to CSV.
I second Waistline, I use it daily for calorie tracking and once you initially set up your foods its great. Sometimes, I have had to edit the name to be something easily searchable instead of the name openfoodfacts returns. As well, some foods are way easier to measure if you use the 'per 100g' setting when setting up the food. After doing that, then change the names/other attributes, because changing to 'per 100g' overwrites the existing record.
For workouts I keep it simple and use GymRoutines from F-Droid.
I had the same problem with wger, tried it and it wouldn't even let me select exercises from the list in the android app. I guess you could do it from the website but I just found it to be confusing.
The way that I worked around this issue was to add the workout plan via a web browser in a PC. It syncs with the app and after that it is working fine.
Now that my account passed the trial period I can even create workout exercises which I didn't try yet so I can't comment about it.
Otherwise this is the first decent workout open source app that I found that works for me.