Although this course is recorded on the Godot 3.X engine and I am using the latest 4.1, it's still a great course to follow/buy if you want to use it in the 4.X version.
There are a few (minor) differences/ obstacles, but you should easily find the solution. The syntax has changed a bit coming from Godot 3.X, but within 30 min I was up and running.
The course itself is really detailed and well explained and I problably will never use JSON again as a datasource (in Godot).
I am currently half-way the course and I am enjoying it, It has helped me understanding Resouces in Godot and how to use them!
So thanks for creating this course, it is abolutely worth the (full) asking price.