There are other char plotters for Openplotter

[e-sailing]

Avnav does need nmea0183 gps data on 10110 (standard SignalK 0183 port). On the panel side Avnav can also show SignalK data.
I think your gps data is comming from pypilot in SignalK format.
Try to convert SignalK gps to 0183 with the SignalK plugin "signalk-to-nmea0183" (Convert Signal K to NMEA0183).
I think minimum would be to check RMC.

("fromAvnav" is only needed if you want to send RMB sentences from Avnav to SignalK to your autopilot.)