Jandy 4-Function Spa Side Remote

That is a statement about the relay board specifically, which is the part of the system documented here. Whether the mainboard behind the display exposes switch inputs of its own is a separate question, and the answer decides whether this remote can be supported at all.

What the remote actually is

• Four momentary contact switches, typically filter pump, spa, heater and one auxiliary.
• No addressing, no protocol, no power requirement of its own.
• Hard-wired back to the controller through conduit run before the deck is finished.

If inputs do turn out to be available

The wiring would be conventional: each switch closes between its own conductor and a shared common, and the controller debounces the closure and acts on it. The physical install is the demanding part — conduit has to be run from the remote location back to the equipment pad before the deck is poured, because retrofitting it afterwards means breaking concrete.