I think I can clear this up.
OP, by "GPS" is what you really mean being able to see maps on the tablet? This requires a data connection for the tablet to contact Google (or HERE) servers to get the map imagery. If you do not have a network connection on the tablet, it will be able to locate you with the GPS built-in to the tablet -- which virtually every tablet has these days -- but will not be able to give any meaningful visual location on the map because it has no imagery.
The solution to this is to use a phone that can be set up as a wifi hotspot/access point. I'm not familiar with iOS and iPhones, so I don't know if this feature is available, and how to set it up. I'll leave it to iPhone users here to address that.
If you have an Android phone, especially a pretty new one (last 12 months), it probably has a Wifi Hotspot or Wifi Tethering feature in the settings somewhere. Turn this on, connect your tablet's wifi to your phone, and now you have full-function maps on the tablet.
This is what I do.
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Now, if the issue is that you truly don't have GPS on the tablet, there is a solution on Android to make your phone act like a Bluetooth GPS module, transmitting GPS data over BT (this is an app on the Google Play Store). A different app (also on the Play Store) can be installed on the tablet to use BT as a GPS provider for the system. With this setup, even if you don't have GPS on the tablet you can use your phone GPS to provide location data to the tablet.
I don't know if there is anything similar for iOS -- those experts will have to speak up and cover that platform.