Hello,
Teltonika router's GPS functionality comes from integrated LTE module. RUT955 Kxxxxx router uses "Quectel EC25-V" LTE module, which has GPS functionality. You can see confirmation of this in Quectel's official website:
https://www.quectel.com/product/ec25.htm
You can also confirm that yourself, by simply connecting GPS antenna to the router and enabling GPS functionality in "Services -> GPS -> Genaral" menu. After doing that you will be able to see device's current location in "Services -> GPS -> MAP" menu.
Note: you do not need SIM card to use GPS functionality.