Does my IPad Pro have GPS

It will only if you purchased the cellular version. The Wi-Fi will determine relative position based on routers and IP addresses. And, cellular will work only so long as you are in range of cell towers.

Mapping Apps, such as Navionics, are critically dependent upon Location Services.

Unlike your iPhone and WiFi & Cellular models of iPad, WiFi Only iPads do not have any GPS location capability with which to directly determine their location - and as such are completely reliant upon their network connection to infer an approximate location. This limitation has further implications in that mapping Apps installed on your iPad cannot estimate your location without a WiFi network connection; no “moving maps” when away from home!

For WiFi Only models of iPad, your approximate geographic location is estimated from a “database lookup” of (a) your WiFi Network Name (SSID) or detected neighbouring WiFi networks - and (b) the “public” IP Address provided by your Internet Service Provider (ISP). 

If the mapped WiFi network name or IP Address are not available within the applicable databases, or if this information substantially differs between sources, then your approximate location may not be computed. This situation often occurs if you are in a remote/rural location where neighbouring WiFi networks are scarce - or if connecting over satellite or VPN connections.

Network IP Addresses and WiFi networks are frequently mapped in urban and cosmopolitan areas (including “crowd source” techniques) and as such approximation of your location from lookup against these databases can be provide relatively high accuracy. As population and network density diminishes, this mechanism becomes progressively less reliable.

If purchased as a Navigation device, I regret that your chosen model of iPad is unsuitable. You need a WiFi+Cellular model.

However, a WiFi Only iPad can be augmented with an external dedicated GPS Receiver (e.g. BadElf) - connected via Bluetooth or direct via USB.