Slopes are part of the bonus topics I'd like to touch on. It's similar to 2D, it's mainly a matter of using move_and_slide_with_snap instead of move_and_slide. It takes some extra changes, as you have to turn snapping to the floor off when you want the character to jump.
I'm looking forward to more feedback!
Note that this may take me time to add more content to this course. Due to our budget and limited revenue, I have to find ways to get some money in at the moment - and Godot courses don't sell that many copies.