Transponder signals indicates that the aircraft is undergoing test-flights, over the skies of Boeing's facility in Seattle. This IN 328 Tail Number Airframe is, currently, flying with the Civilian Registration N490DS identification.
First of the purchase of 6 additional Boeing P-8I Neptune Multi-mission Maritime Surveillance Aircraft the Indian Navy has opted for, it could be flying to India, later this year. While the photograph is of it's flight from last week, September 04, 2020, it likely took to the air the first time sometimes in March 2020. Sweet capture, courtesy LunchWithaLens.
Order finalized in December 2019, an adequately kitted aircraft flying in 4 months - that's quick. Being based on the widely popular, much produced Boeing 737-800ER civilian aircraft lying around it's plant, would have played a role in this shortened 'Release To Market'. Though the P-8I incorporates a fair amount of India-specific systems, it shares major commonality with the baseline P-8A, Boeing originally designed for the US Navy. A mature Supply Chain, coupled with systematic Vendor cultivation, not to mention, anticipation of a re-purchase, all played a role.
This photograph, above, from the 2019 Malabar-series Joint Naval Exercises, shows both variants of the P-8 together, along with the Kawasaki P-1 #, serving with the Navies of USA, Japan & India [L-R]. Tracing a line, joining all 3 Nations, it cuts an Arc of Democracy, slicing through PRC.
Interesting development.
# - Aircraft incorrectly identified earlier. Hat tip to @ThingNavy for pointing it out.
Godspeed