It is certainly not to the same levels of accuracy as the capabilities provided by the setup presented here, but I recently put together a stratum 1 NTP server (there are lots of various instructions online for setting up something like this [0][1]) on my LAN using a Raspberry Pi 4 and a GPS module with PPS output [2]. The setup took a bit of fiddling and experimentation to get working reasonably well (and it still has some glitches when trying to initially sync the time after a reboot), but once it's synced it does track time from GPS very reliably.

For anyone who might be looking for a reliable, accurate NTP time server but isn't interested in the hassle of setting up and configuring the hardware/software themselves, there's also this little appliance [3] I am also using that does something very similar at a great price point (no affiliation here; just a very happy customer). I have both my RPi setup and the NTP200 appliance tracking each other on the same LAN, and they generally agree on the time to within single-digit microseconds, which I think is about as good as one can get with any NTP setup on an Ethernet LAN, at least without resorting to more exotic things like OCXOs, hardware timestamping, etc.

[0] https://austinsnerdythings.com/2021/04/19/microsecond-accura...

[1] https://www.jacobdeane.com/iot/2020/building-a-gps-based-tim...

[2] https://www.adafruit.com/product/746

[3] https://centerclick.com/ntp/