FWIW, my GATE high school offered an entire year of geometry for 9th graders: one semester proof-based geometry (proofs every night, I loved it!), and one of coordinate geometry. (It was assumed that if you were going to this school, you had already taken algebra I). (Take this info as you will, as it is a couple of decades old. But just know that they managed to fill out an entire year of geometry and make it rigorous and interesting).
And as an aside, there was also a separate track of math classes, like bluemagic mentioned; kids were randomly assigned to one track or the other. Luckily I was in the first track, since my family moved after my sophomore year. So, it's not a new concept, but I don't know how successful it was.
