This should be easy and cheap, but I am somehow finding only expensive and complex "solutions".
I have a SPST switch that turns on two bulbs, one inside the front door, one outside the front door. Since the 1950s, one flipped the switch, and both lights would light. Simple! Next to that switch is a 2nd SPST switch that controls a wall outlet, intended for a lamp to turn on when entering through the front door. Also simple.
THIS is likely how millions of front porches have been wired, including all the post-WWII boom housing, so there's "a market need" here.
Now, enter Hubitat...
First, I got a motion sensor, and put a 2-inch length of 3/4" PVC pipe "snout" on it to make it look only at the welcome mat. The idea was to detect the arrival of packages delivered by people who consistently refuse to ring the bell, and use a Tasmota SonOff to make the door bell ring a distinct "package" rapid-triple-bong. Sounds simple.
But the Hubitat can't receive Zigbee signals from devices on the front porch, even in our tiny cottage, so the solution is to take a Tradfri socket, remove the plastic case, and wire that into the weatherproof housing of the front porch light to relay the Zigbee signals. This is great, but now power has to be on all the time to the fixture. So, the switch is on all the time, and the Tradfri makes the porch light "smart".
But now the inside foyer light is also on all the time, so another smart bulb for the foyer. Now a question of manual control arises, as there is no sensor-based scenario where I want to turn on either light. And this is where the wheels come off.
A simple obvious solution is to hardwire the circuit to "on", and install a pair of smart switches to signal the Hubtait to turn the lights on and off individually or together. But its $60 for a no-neutral switch, none of them are simple toggle switches of the traditional sort, and this is not "worth" $120 plus the $10 Tradfri, and the $10 smart bulb (total $140!!!). The alternative is to hardware the 120Vac, and wire a older reed-switch door/window sensor to each switch to control the outside and inside switches.
But now batteries have to be replaced, and they are behind a switchplate. This is getting stupid. So... a tiny power supply to put out 3VDC to power the two door sensors?
There has to be a cleaner implementation for replacing a very standard SPST switch that interrupts the hot wire to one or more bulbs, and does not demand that I roll my own kludge!