Learn to create Python3 plugins

[z-uo]

I want to learn to create Python3 plugins for GIMP. And when I search I do not find much examples on the web so I ask here. The main thing that I want to do (and document on this thread is):

1. goat-exercise tutorial and learn
   
2. port a plugin from python2 to python3 (maybe I will port gimp-balloon-plugin)
   
3. create AI based plugins using torch AI like GIMP-ML do with Opencv. For example some interesting features are:
   

• OCR: to recognize and maybe translate some text inside images
  
• Super resolution: increase the resolution with a deep algorithm
  
• Inpainting: redraw some removed areas automatically
  

I start from the point 1:

• GIMP 2.99.8 installed with flatpack on Opnesuse Tumbleweed
  
• I put goat-exercise into ~/.config/GIMP/2.99/plug-ins/python
  
• Restart Gimp
  
• I do not see nothing new into Filters > Development > Goat exercises
  

I miss some configurations? What should I see in there?