Nope. A deviation is not required. At least according to the Richmond FSDO (phone call) and an email from the ADAPT (portal to request deviation) folks.
Thank you for your inquiry.
There is no need to request a deviation after the installation is complete. Upon completion of your flight, please request a performance report using the following link:
This will let you know that your equipment is working properly or, if not, which parameters need to be checked by your installer.
If you have any additional questions, please feel free to ask.
FAA ADAPT Support Team
Sent: Tuesday, December 31, 2019 1:10 PM
To: 9-AJO-ADAPT-Help (FAA) <firstname.lastname@example.org>
Subject: New ADS-B installation
I am equipping 1/2/20. If the installation checks out on the ground, do I still need to request a deviation through ADAPT? In other words, am I not technically legal until I get a PASSED performance report?