To my knowledge, you can only call a microflow (server side) from a nanoflow (client side) and NOT vice versa.
Are you revering to a progress bar as in how the execution is? If so, then that is something I also want to know. The only thing that I could find is the blocking message during execution
You cannot call a nanoflow from a microflow as that doesnt really make sense.
A common implementation pattern I have seen for this is to call the microflow from the nanoflow, and display/hide a loading dialog in the nanoflow before/after the microflow call.