Help with a symlink in /dev

I'm trying to get openNTPD running on nixos with a GPS as a reference. I have found some openNTPD configuration examples that have you create a symlink from the serial device to /dev/gps0. How would I do this from the nix configuration file? Would it be better to do something with udev to identify the GPS and bring it up as /dev/gps0?

Thanks in advance!