My understanding would be that the NMEA driver (20) is used to get both the second numbering from the NMEA data stream as well as the PPS pulses from the same driver, as also discussed in another recent thread. Note the server address, the RefID, and the lack of a star in front of any of the other servers on the billboard.
Thanks for sharing your solution! Small item, but quite interesting to see that BSD natively supports both DCD and CTS lines to serve as PPS input for kernel PPS. Linux typically only uses DCD, like illustrated by Dan Drown adding PPS capability to the CDC USB-UART bridge driver, as shared in a recent thread. Avoids having to muck around with the cables/connectors if a GNSS unit natively provides PPS on the CTS pin, as various units do.