I totally hear you!!! I firmly believe in math by ability, not by age, and these limitations on when kids are offered Algebra and really exciting topics is ridiculous. This is why people homeschool. My kid was bored out of his mind. He needed a challenge. He was discussing probability and fractions in first grade. By 5th grade, he’d already chatted with us about most of the topics that were being covered. We never did workbooks, but occasionally, we’d show him a math topic, and that was how he learned.
Even in the “accelerated” class, his teacher would say things like “Does anyone other than -my kid- know the answer to this question?” Or “-my kid-, could you please let me finish the question before you answer?” Sure, it’s cute that he’s smart, but in reality, these are sure signs of a kid that is assigned to the wrong class and not being challenged. It’s demeaning to him. I can’t imagine what he’d done for another 3 years of math class if he hadn’t started Algebra in 6th grade. I can’t imagine him waiting until 9th. That’s like trying to date someone for 10 years and staying chaste. About 3 years in you either get married, or you leave.