You will find these tutorials very helpful as you start your Ultra Extension Framework (UEF) developement.
How To Ultra Extension Framework - Scott Hurrey DevCon 2020
Ultra Extension Framework
This tutorial starts with a Python-based LTI 1.3 Hello World application and shows you how to convert that project into a UEF integration.
The tutorial is also available in a Youtube playlist, if you prefer to learn in this way. If you prefer to go directly to Youtube, click here
You may find the related code used on the videos here: GitHub BBDN-UEF-Python
Before releasing a UEF integration, that uses the UEF Premium APIs, to production you will be required to meet a certain level of Blackboard Partnership. See Become a Blackboard Partner.