Sorry for the late reply.
Currently NMEA output is not supported. It is possible to generate NMEA similar to our example of inputting NMEA (https://github.com/waterlinked/examples/blob/master/externalNMEA.py) if you are comfortable with programming. (Here is an example of generating NMEA: https://gist.github.com/JoshuaGross/d39fd69b1c17926a44464cb25b0f9828)
We have been evaluating supporting NMEA so if you have additional information on what sentences should be generated that would be helpful. I would guess GPGGA or GPGLL.
Should the prefix “GP” be user configurable?
NMEA over UDP is easier for us to support than UART.
(PS. If you haven’t already, you should upgrade to release 1.4 for better performance: https://update.waterlinked.com/)