I have a fitness tracker band from mi (Xaomi). It has an Android app associated with it on my phone called mi Fit. Now, I want to know how to fetch all or some of the tracked data i.e sleep quality, steps taken, calories burned, distance covered etc. into a file that could be read by Windows or Android programs to create a graph out of it. If not, then is there any way to just combine and fetch the data?
If it is acceptable for you to use a separate app to collect this data, take a look at GadgetBridge (available on F-Droid). That's an open source app supporting many gadgets, a.o. Pebbles and Mi-Bands. It allows you to export the collected data (see e.g. here). Since v0.24 you can even set it up to do so automatically/periodically.