from my emails when I was onboarding with OO -

Me asking -
"Good morning, I just wanted to clarify and confirm that PRIA forms are only required for 135 and 121 air carriers ? In other words, you do not want or need me to fill out PRIA forms for part 91 employers ?
Thank you"
Their response -
"You are correct, just the 135 and 121 carriers."

and from the instructions on the 8060-12 form -
"A list of specific drug and alcohol testing records to be furnished through this request is provided in Part I of FAA Form 8060-12. Part I is also used by the hiring air carrier or other person who has employed the individual as a pilot at any time during the 5-year period preceding the date on the employment application:"