Nokia 8.1 has a double channel LPDDR4X type of 4GB RAM.
Yes, Nokia 8.1 does have the 3.5 mm headphone jack. It also has Bluetooth A2DP support.
In the official packaging of Nokia 8.1 - you will get your Nokia 8.1, USB Type C cable, Power adapter, Headset, Quick start guide & SIM door key.
Yes, Nokia 8.1 is the metal body phone.
Yes, Nokia 8.1 display works as a flash under low-light conditions.