Configure editing form widgets using PyQGIS

As I was preparing a QGIS Project to read a database structured according to the new rules and technical specifications for the Portuguese Cartography, I started to configure the editing forms for several layers, so that: Make some fields read-only, like for example an identifier field. Configure widgets better suited for each field, to help the user and avoid errors. For example, date-time files with a pop-up calendar, and value lists with dropdown selectors. Basically, I wanted something like this: