I hope someone helps you bc I’ve been curious for some time. I do believe it require Javascript. I know the basics of JS but using it with behaviors and things like containers still confuses me.
This link might help.
https://docs.gdevelop.io/GDJS%20Runtime%20Documentation/modules/gdjs.html
The platform and pathfinders both use a manager.
It says here that the behaviors have to declare themselves.
I’ve tried understanding it by looking at the user created nav mesh pathfinder but I couldn’t understand the process.