> How much aeronautics/airworthiness/safety R/D is actually conducted by the FAA?

Virtually none. It's widely recognized that airine mfg. technology is a rapidly moving target, and the FAA is not in the airline mfg. business.

The FAA is in the business of collecting and reviewing certification data, which is why the fake MCAS paperwork is a really big deal.

NASA operates the X-planes R/D program, not the FAA.

https://www.nasa.gov/centers/armstrong/images/X-Planes/index...