I don't have any specific ideas, but LoRa radio modules might be cool to tinker with. Communicators/gateways built with them could be useful in situations where you can't or don't want to send traffic over third-party networks. If you implemented some decent encryption on top of it, it'd hypothetically be untraceable. And not that security-through-obscurity should ever be relied upon, but I don't know if anyone would even think to monitor those frequencies.
I don't have any specific ideas, but LoRa radio modules might be cool to tinker with. Communicators/gateways built with them could be useful in situations where you can't or don't want to send traffic over third-party networks. If you implemented some decent encryption on top of it, it'd hypothetically be untraceable. And not that security-through-obscurity should ever be relied upon, but I don't know if anyone would even think to monitor those frequencies.