I think, in your case with those specific signalk keys available, your best option is to configure signalk to send RMC and APB messages to pypilot's TCP/20220 socket. To do this, you'd need signalk's 'signalk-to-nmea0183' server plugin from the built-in appstore, configure that plugin to generate RMC and APB messages, then add a Data Connection with NMEA0183 and TCP client settings pointing to pypilot's IP address and TCP/20220 listening socket, and set Output Events to nmea0183out. If pypilot receives those messages, it will enable the GPS mode which will follow a track/route.
The option that you seem to have heard about is related to the pypilot native, internal communication mechanism, that is accessible through some TCP socket and can be talked to through a python pypilot_client. With that, you could in theory get the whole thing working as well, but it's the long way home, not the royal way and it might break in the future, so I would definitely not recommend that.
Another option, that will not work, would be to use the native, zero-conf interface between pypilot and signalk. Pypilot requires steering.autopilot.target.headingTrue, which you don't seem to have in your signalk database.
The option that you seem to have heard about is related to the pypilot native, internal communication mechanism, that is accessible through some TCP socket and can be talked to through a python pypilot_client. With that, you could in theory get the whole thing working as well, but it's the long way home, not the royal way and it might break in the future, so I would definitely not recommend that.
Another option, that will not work, would be to use the native, zero-conf interface between pypilot and signalk. Pypilot requires steering.autopilot.target.headingTrue, which you don't seem to have in your signalk database.