There are great app recommendations here. Perhaps not the habit tracking type, but I love FitoTrack for tracking my runs. No social, no BS, just pure local metrics. Not perfect but entirely usable and serves its purpose.

https://f-droid.org/packages/de.tadris.fitness

Edit: what I love most about all these apps is that they are so lightweight. I have so many apps today which are well above 100MB, sometimes around 500MB and I'm not talking games.

This is so outrageous to me. All of these open source apps by comparison are 10MB or less. Absolutely beautiful.

I recommend also something similar in terms of time: https://f-droid.org/packages/com.razeeman.util.simpletimetracker/

What is 2+2 minus 1

https://f-droid.org/en/packages/org.isoron.uhabits/

Loop Habit Tracker is an app I've been using for years now to help me maintain daily, weekly, and monthly routines. I find it's "sticky" notifications very useful.

Track & Graph has some more options to choose from : https://f-droid.org/packages/com.samco.trackandgraph/

i use both

Installed it, seems simple and efficient!

Would be nice to see all stats at the same time (and machine learning predicting them in the near future ...).

I use it all the time when walking a track. Pretty good app, and it lets my brain not worry about losig track and wondering if I really did walk around the desired amount of times.

Does the export have a timestamp attached?

OK but what does it do?

I use Table Habit to track my habits: https://f-droid.org/packages/io.github.friesi23.mhabit

It has a good looking interface and charts too.