I recently built a stratum 1 time server for my network. I used this blog post as a recipe: https://blog.networkprofile.org/gps-backed-local-ntp-server/
It’s capable of working stand-alone without a network connection, some would say as an orphan, but having the GPS PPS signal makes it highly accurate within 200 or so nanoseconds and I’ve seen better on mine:
I need to figure out how to collect statistics to graph the data and possibly make some adjustments to the configuration file… but for now I’d say that the clock being accurate to 0.000000163 seconds is good enough for my needs.