Hardware Autopilot and GPS RTK for a boat

Hello, I want to build a prototype of a maritime vehicle and I have questions about the hardware to use.
I was analyzing options and for the autopilot I chose the Pixhawk 4 and for the RTK GPS I chose the Here3 & Here+ RTK Combo, are both hardware compatible? What other RTK GPS would you recommend? I’m looking for cheap options. Thanks

There really isn’t a cheap option, though the ones you’ve chosen are likely the least expensive. They are also the least performant, so don’t expect to achieve consistent RTK Fixed status with that hardware.

A pair of these SimpleRTK2B boards will perform much better. Install one on your vehicle and connect the other to your laptop and use Mission Planner’s Optional Hardware/RTK/GPS Inject feature to operate it as a base station.

Another option that’s a little more convenient and packaged well is CUAV’s C-RTK 2HP series, which includes the ability to achieve a GPS yaw solution with a single onboard module. The base station upgrade is a little expensive, but it’s good hardware, and precision doesn’t come cheaply.

Thank you very much for the feedback, I really don’t know much about this, I’ll keep that in mind.