I think it depends on whether the use is classified or not. I'm not aware of iPhone supporting red/black separation, not to mention a model without cameras for use in secure environments.

I'm not aware of any consumer phone that would follow a pure red/black architecture.

There are a bunch that are CNSSP-11 compliant, though: https://www.nsa.gov/Resources/Commercial-Solutions-for-Class...

I was careful to use past tense, as it was a fact, but I don't know now.

iPhones can be supervised and/or enrolled in MDM that allows for very high-granularity control of settings and logging etc