There are more python bindings aside from gz-transport13. Probably not easy to found in documentation so you can check your system using:
$ apt-cache search ‘python3-gz|python3-sdformat’
Some of have tutorials or documentation. A search in the gazebo_test_cases repository (used for release tutorial parties) on Harmonic and python can point to some of these: Issues · gazebosim/gazebo_test_cases · GitHub
You can also find examples and test directly in the code inside each of the repositories python* directories. The gz-math one gz-transport/python at gz-transport13 · gazebosim/gz-transport · GitHub.
Hope it helps.
P.D: I created a PR for my personal gazebo-doc-index so it helps other people to find this kind of information. Include a section on programming by j-rivero · Pull Request #1 · j-rivero/gazebo-doc-index · GitHub