So I recently bought myself a Pinephone with the aim to use it in one of my projects. I need to read the location data and relay it to another computer. How does one go about getting the location data from the command line interface, CLI?
What level are you looking at, and on which OS?
Basic low level access via the modem's USB serial interfaces is described in the wiki, with links to Quectel's GNSS AT commands:
https://wiki.pine64.org/wiki/PinePhone#GPS_.2F_GNSS
Most OS flavours have another layer running to mediate access to the modem and/or GNSS though - ModemManager or oFono for the modem, and geoclue and/or gpsd for the GNSS data. They may have other mechanisms for doing some setup too - eg25-manager has certainly done things with GNSS configuration at times. You can either access it via these mediators (mmcli location commands for example) or stop those services before accessing the USB ports directly.