The phone will sport a 5.5" OLED panel from LG (resolution and aspect ratio unknown), HMD's first OLED screen. The chipset is this year's Snapdragon 835 and it will be running Android 8.0 Oreo. RAM is not mentioned, but the storage is a generous 128GB (eMMC sourced from Samsung).
The main shooter on the back of the Nokia 9 will be a 12MP + 13MP dual camera. The selfie camera is a surprise at a mere 5MP (the Nokia 8 has a 13MP front camera).
The final details divulged by the FCC are a 3,250mAh battery with fast charging (18W) plus some in-box items - a charger, USB cable and headphones (seemingly each sourced from one of two suppliers).