Yes, Oppo R17 Pro has a dedicated 3D camera at the rear.
Yes, Oppo R17 Pro does have the GPS support.
No. Oppo R17 Pro does not have the MicroSD card slot. The phone comes with huge 128GB internal storage and it also has OTG support.
No. Oppo R17 Pro has an only dual sim slot. You cannot use MicroSD card with the Oppo R17 Pro.
As of now, Oppo has not announced any support for 5G network on Oppo R17 Pro.
Oppo R17 Pro has a lot of points going in its favour like excellent set of cameras, great display and design as well as top-notch performance. I think Oppo R17 Pro can give solid competition to OnePlus 6T going by the overall performance.