With the NMEA2, if you can connect your Raymarine Autopilot NMEA input to the NMEA2 "output" (A3/B3) then you should be able to route GOTO waypoint commands from a suitable navigation app.
Use TCP>P3 to route from TCP to the P3 output of a NMEA2.
UNFORTUNATELY, The Navionics app itself does NOT send suitable goto commands, but other apps can, and do. (see my earlier post).
Another way to send commands is to use Seatalk, but that requires a NMEA3! as this is the only NMEAx unit that can "SEND" seatalk. all the others can only receive Seatalk.
Discussion and support for the Nmea2Wifi multiplexer - a 2-input Nmea 0183 wifi multiplexer.