[Red_Leaves_Flyy]

If it’s baked into the firmware of major cell phone manufacturers components how many people would it take?

A team of CS engineers at NSA.

1-2 people in privileged positions either at the point of assembly/programming deployment to ensure the code is delivered. - for each company which is basically just alphabet, Samsung, and Apple or their chip providers which is about five companies.

This does not seem all that impractical - how many people are dumping firmware from in the wild consumer cellular devices and reverse engineering enough of the code to see if this functionality exists or not? Anyone with that skill is likely making a killing doing other work.