It'd be more correct to say pseudorandom. The way I was taught ZKPs was in terms comparing the output of pseudorandom number generators seeded by a challenge an

It'd be more correct to say pseudorandom. The way I was taught ZKPs was in terms comparing the output of pseudorandom number generators seeded by a challenge and a shared secret, but you can also explain it in terms of hash functions instead. What I was thinking was that the random number from GPS (or some sequence derived from it) could serve as the challenge, basically akin to a 2FA scheme like HOTP. Or a variety of other schemes, hinging on the trait that you can't predict the next output of the random number from GPS.