The letter notes that OnePlus wants to rebrand the device as its own.
OPPO has informed the FCC that it has allowed OPPO to market CPH2387 as its own device
The battery cover will be stamped with a OnePlus logo and the color of the USB cable will be changed to red from green. The main camera will be replaced with a higher resolution 50MP sensor and the device will run OxygenOS instead of ColorOS. The dimensions remain the same at 163.74 x 75.03 x 7.99mm and the battery capacity also remains unchanged at 5,000mAh.
The mystery OnePlus Nord device will essentially be a Oppo A57 4G with a different main camera
Not much else of importance is mentioned in the documents but if you are wondering what the mystery OnePlus phone could offer, the Oppo A57 4G features a 6.5-inches LCD screen and the MediaTek Helio G35 SoC and supports 33W charging.