Many off-the-shelf pool automation systems use this relay (Omron G7L-2A-BUBJ-CB). I comes in a 24vdc or 120v coil. Then you can drive it from any z-wave switch/module, both for the motor starter and the speed control as it’s a DPDT relay. You’d need two relays, one for each function. You can drive them from a dual switch module from Aeotec or Qubino, or any smart switch. I used this method prior to installing the Aeotec Heavy Duty. It worked great.