Nanosecond level sync is fairly achievable with Precision Time Protocol [1]. This is common in most media systems where small amount of drift will cause phase issues with audio. Not my area, but I believe it's seeing a few using in the DC space too [2] where they may be strong requirements around event ordering for distributed systems.
The White Rabbit Project [3] also extends it to the picosecond realm for research control and instrumentation systems.
Not a scratch on this project though.
[1]: https://en.wikipedia.org/wiki/Precision_Time_Protocol
[2]: https://engineering.fb.com/2022/11/21/production-engineering...