I often hear the excuse that mainstream courses like Algebra and Calculus are taught first and in a boring way because you have to learn mechanics before getting to the good stuff.

However I don't see why they couldn't start a Calc course with one of those cool documentaries on Newton. For me it was incredibly motivating to hear the questions that drove the theory.

Beyond that it seems certain classes like discrete math or combinatorics might allow more creativity and experimentation in secondary school without requiring a ton of foundation.