Ron is correct, your Nurse Practitioner can certainly perform the medical exam, however the Comprehensive Medical Exam Checklist will require the signature of a state licensed physician.
Physician Qualifications. The FAA relies on the determination of each State (as well as each territory and possession of the United States) as to which persons it will license as physicians. If the person holds a license as a physician issued by any State, territory, or possession, then they meet the requirement as a state-licensed physician. The FAA notes that all States license medical doctors (M.D.) and doctors of osteopathic medicine (D.O.) as physicians; although Federal and some State laws may permit the licensure of other persons, such as doctors of dental surgery (D.D.S.), as physicians. While the FAA expects that these specialists (e.g., D.D.S., dentist, podiatrist, etc.) who do not also hold an M.D. or D.O. would not have the breadth of training for a BasicMed medical examination, the FAA will rely on each State-licensed physician to determine whether he or she is qualified to conduct the medical examination. https://www.faa.gov/documentLibrary/media/Advisory_Circular/AC_68-1A.pdf
My PCP is a Nurse Practitioner. Can she sign off on the BasicMed?
Here is the FAA's official answer:
Q46: Can a physician extender (such as a nurse practitioner or physician assistant) conduct the medical exam?
A: A physician extender is a health care provider who is not a physician but who performs some medical activities typically done by a physician. Physician extender practice privileges and requirements for physician supervision vary by state. Physician extenders are generally nurse practitioners or physician assistants. Registered nurses, medical technicians, and medical support personnel also assist with certain elements of an examination but are not considered physician extenders. Section 2307 of FESSA did not specifically exclude participation of a physician extender. However, under BasicMed the physician is responsible for conducting the medical examination and must be the signatory on the CMEC.
So, what does it say on her state license? Nurse or physician? If it doesn't say "physician", she can do all the work, but she'll have to get her supervising physician to sign it.