I'm currently up to Mendix 10.24.8 and see that (still) the only two types of loops in a microflow or nanoflow is to loop over a list of objects or a while loop based on a boolean expression.
I had a need to do something for every entry in an enumeration but yet there's no declarative easy way that I could find to do it. I ended up running the model reflection, retrieving the enum, and then retrieving its values over an association and looping over that as a list of objects. I then had to copy/modify the java action from Community Commons that is the one that gets an enumeration from string to get the ENUM reference for each string value retrieved in the model reflection.
But why so many steps? An enumeration is just a list of captions and key values. Why can't we loop in a nanoflow or microflow over the enumeration definition without having to populate the model reflection and retrieving?
Quite inconvenient, indeed.
You can also create an entity containing only the enum value, and then create an object for each enum value (e.g. via afterstartup). Then retrieve all objects from DB, and loop over those.