You can acheive it by using nanoflow's Sign in function.
At first, You have to make a Pin Entity that has a 1-1 association with User Entity.
Pin Entity has a Pin number and password of User.
The flow will be
1. Retrieve user name from user's input
2. retrieve Pin entity by association.
3. compare user's credential info with pin entity
4. if user's input is match with pin entity's password or pin number then use nanoflow client activities 'Sign in'
You can achieve this by creating your own custom login page.
1.Go to your project.
2.Navigate to theme folder.
3.Edit login.html page and add all the input fields and button required .
4.Synchronize the project and run it. It will work
We have multi factor authentication widgets available in the app store.. you can use that if the pin is changing or
When user enters the pin and username you need to have a different flow in the login microflow where you can verify if the given combination is correct and proceed with validation