GPS works with a fully offline and in airplane mode device. GPS is 100% passive, unless you want faster initial fix, for that A-GPS comes into help and require data connection.
But plain nice old reliable GPS is 100% passive and works fine with totally disconnected devices. Actually original GPS devices (who remmebers those...) where 100% offline. Maps on the SD card, no live traffic or accidents data, nothing fancy. Yoiu had to purchase yearly maps updates too, what old times.
What is the point in installing OpenWRT on something that is not a router? I use it, i have it on a few different WiFi access points...
but what would be the reason to install on a regular pc, whether on VM or not?