There isn't that much boilerplate with pygame (I've taught middleschool students pygame in the past); I'm not sure if it makes sense to move things into a framework, and have a lot of configuration by convention, when the goal is education.
Another advantage of Pygame Zero is that the author was involved in the creation of Mu, and so Mu comes with Pygame Zero pre-installed. Having to install Pygame via pip would be a challenge for many kids.
Anyway, Pygame Zero includes all of Pygame so you're free to introduce as much of it as you like.
There is no logical reasoning why those two variables are globals, and what other globals might have special behavior.
If you need magic variables, you haven't actually fixed the boilerplate problem.