Andy,
You would only need to use a "closed/thrown" sensor if you wanted to know the actual state of a turnout, not just what it was told to do.? As I mention in the my reply to Dick,? what I had in mind was messaging the "ONESENSOR" turnout feedback in the JMRI documentation.
As to where you would put them, one PI or esp32 based MQTT node should be able to handle 8-16 or more (depending on the chip) I/O control lines.? Couldn't you could match up the turnout control with the turnout feedback sensor on the same controller?? Or couldn't you have turnout only nodes and sensor only nodes? ? Whatever works for you.
In you example, wouldn't "routes" be a solution to throwing multiple turnouts at the same time?? No reason a turnout node could not be setup to handle routes.? A bit more complicated, but I think doable. Looking at your photo I see a lot of what I consider crossovers.? Couldn't you just wired the turnout motors to code/throw turnouts with one command?
richard
