Range is hugely variable - if there is a big hill in the way, the range can be 200m, if it’s all flat, it could be 20,000m. Hard to say without knowing the location.
Apart from the fact that the OLG01 is clearly stated on the Dragino website to not being suitable for LoRaWAN and is incompatible with TTN, you will need to add a Quectel EC25 suitable for your region if you want it on mobile internet. So not a good choice at all.
Do you have experience in micro-electronics & writing firmware in C? If so, that’s great. If not, you can learn. But it can sometimes be less expensive to buy pre-made modules.
Just to be clear, you need a full LoRaWAN 8 channel gateway if you want to use LoRaWAN. Search the forum for recommendations on options with mobile internet.
As this is the LoRaWAN on TTN forum, the approach is buy proper kit - like an 8 channel gateway - like the DLS08N (not sure if there is mobile internet for that) or any other compliant gateway you can find using, as suggested, the search on the forum.
However the laws of physics apply to all radio systems, so your terrain will introduce a universal problem. If a device is near a wall at the bottom of the hill and the gateway is at the top (gateways high up are good, but it leaves an immediate dead-zone right underneath), then the device may not be heard, even if it’s only a few hundred meters away:
Ideally you want gateways on the top of each of those stacks surrounding the devices, so the device on hill A is heard by gateways on hills B, C & D, but not likely to be heard by the one on the same hill.
As your terrain is particularly ‘interesting’, spending some time learning about antenna’s propagate a signal would be a good thing.
