Just launched my creation powered by a Rock PI S.
The NTP250 provides a compact stand-alone GPS-based NTP Stratum 1 network time-source. Based on the Rock PI S, and a base board with power supply, GPS and other logic in a small case.
Note that the PoE Enabled Rock PI S SKUs works great with a Winchen WC-PD13C012I PoE module taking the 4-pin PoE header on the Rock PI S and then doing the PoE negotiation and producing an isolated DC output that I can then OR with the DC input, regulate, and then feed back into the Rock PI S. Works great.
More info at https://centerclick.com/ntp/