The avionics package is complete. When ordering from Van's you choose single or dual display, +/- autopilot, Dynon or Garmin, IFR/VFR etc. Van's puts together the airframe components (panel, center console, etc.) and sends them to SteinAir. The folks at SteinAir do all the wiring and send the complete package, including avionics to you. You can even have the panel powder coated and silk screened (a work of art, see pictures at the link below for my build).
With few exceptions , all connectors are attached. All wires, antennas, stick grips, grommets, bushings and hardware are included. You route the harness in place per the Kit Assembly Instructions and are good to go. Connections are included for all options (autopilot servos, ADS-B) so they can be installed later if you wish to defer some parts. Note that to register the plane as an E-LSA, the package must be ordered through Van's. If you choose to source your avionics from somewhere else, the plane would need to be registered as an E-AB.