I'm integrating daily steps walked into my workout/nutrition tracking app EverBeat for Android. I've noticed that this is an important metric for many people interested in losing some weight.
I estimate burned calories on the minute-to-minute level for all activities, which is a fun challenge.
For the steps to calories conversion, I require time and distance walked. Unfortunately it's surprisingly difficult to get some kind of distance information from Android. Google Fit API provides this data, but will be killed soon. The RecordingAPI will hopefully provide this in the future, but not yet...