Yes, Oppo F9 Pro does have the GPS support.
Yes, Oppo F9 Pro does have the OTG support.
No. Oppo F9 Pro has a dedicated MicroSD card slot and 2 dedicated sim card slots. You can use 2 sim cards and a memory card at the same time.
Yes, Oppo F9 Pro does have the face unlock.
The Oppo F9 is among the most attractive in the mid-range today. Unique with that waterdrop-like notch and beautiful with the gradient back with cool pattern underneath.
The Oppo F9 Pro reminds us of the early 2000s when Nokia, Samsung, Sony Ericsson, and others used to come up with wildly imaginative designs all the time. Very few phones these days take any risks with colours, patterns, shapes or materials.