Yup. Software 3-way, or 4-way, or whatever way.
Latest command to be sent gets executed,
regardless of the GPIO input.
The problem with software switches vs. hardwired 3-way is-
with LV, you can't control a series (standard) dimmer,
with LV, if you system fails,
you have no switching control.
With HV 3-way, you still have
physical switching control
and you can use standard 3-way dimmers.
for HIGH Voltage 3-way switching,
High Voltage RELAY outputs-
Use the Normally Open (N/O), black traveler on #14-3 romex
Normally Closed (N/C) , red traveler on #14-3 romex
The Line-In neutral (white) simply passes from the Neutral Line in
to the #14 romex white Neutral line out...
to the white #14 romex of the remote Neutral line load.
Connect your Line Power(in) BLACK to the (C), relay Commuter.
Now, power will flow
to the RED traveler when the relay is relaxed,
and the black traveler when the relay is energized.
At the OTHER end of the 3-way,
your #14-3 romex red and black will plug into
the 3-way Switch Traveler screw lugs..
The BLACK screw on the 3-way is the Commuter (C).
That screw will attach to (P-load)
go to your LOAD (light, whatever).
Tie the white Neutrals together.
If you want to add an additional physical 4-way switch,
just run the red and black #14 romex travelers
to the respective in/out screw lugs on the 4-way switch.
You can add as many functional 4-way switches as you need.
So- 1 of the 3-ways must be the Form C of the Cayenne project,
and 1 must be the physical 3-way to complete the circuit.
You can add additional physical 4-way switches as needed.
See- on a 3-way, one of the screw terminals is painted black. That is the Commuter.
Here's a 4-way switch. Travelers in, travelers out...