Was trying to insert a micro SIM card into the SIM card slot but the size of the slot is too small for a micro SIM. Not sure if the slot is meant for a nano SIM with a SIM card tray (same as how one places a nano SIM into an iphone) since the size of the nano SIM is clearly much smaller than the slot.
That's a good question, however this slot is currently marked as reserved and there are no public details available at the moment. As soon as we can share more information we will announce it in the community.
Have a nice day.