> Humans have a wide variety of biological variation in metrics we think of as linked to "biological sex"

What is the total prevalence of all conditions medically recognized as intersex?

> and those metrics are accessibly mutable.

What is that even supposed to mean?

> What is the total prevalence of all conditions medically recognized as intersex?

Not all biological variation is classified as intersex.

> What is that even supposed to mean?

You can change a lot of your 'secondary sex characteristics' intentionally. This is much easier than removing a limb, and even easier than adding a limb.