kichckcc
Use webhooks. In Alexa, add a webhook as a trigger and a routine to turn off the lamp, and your neighbor just needs to go to this specific url and turn off the light. Simple and fast.
https://trigger.esp8266-server.de/
https://www.amazon.com/Michael-Dworkin-Webhook-Routine-Trigger/dp/B09RGPYHLL
To send manually, all you need is UDP Monitor. More fancy stuff with MacroDroid which has send UDP as an action.
https://play.google.com/store/apps/details?id=com.sandersoft.udpmonitor
https://play.google.com/store/apps/details?id=com.arlosoft.macrodroid
To receive a UDP packet with a message on Windows...
You have to hit the button on the heater to turn it on
Properly programmed Fingerbot/Switchbot will press this button according to a schedule.
If you want to complicate it, you can add a presence sensor to control the bot. The sensor will detect whether someone is in a given area and if not, tell the bot to turn off the device.
Perhaps something similar to SwitchBot Blind Tilt...
Do you mean regular ON/OFF? If so, I've already written about something similar... https://reddit.com/r/IOT/comments/17zaapw/easiest_way_to_control_batterypowered_christmas/ka16uej/
However, when it comes to controlling their functions... would need to know exactly what equipment it is and how it works in order to advise.
I won't recommend a specific socket, but you may achieve what you want by using two switches, switch per cable to disconnect. Or switch without N...
https://itead.cc/product/sonoff-zbminil2-extreme-zigbee-smart-switch-no-neutral-required/
Can I reuse them and not have to pay for a subscription or buy an alarm service?
Reusing these sensors is not very profitable... It looks wireless in the photo, right? You would need to determine what type of transmission there is: RF433 or something else. Then you would have to recognize the codes it generates and build a whole background for it.
More or less... https://www.youtube.com/watch?v=jrto7hc4rtg
In 2023, it simply makes no sense, both financially and time-wise. There are ready-made solutions available and they don't cost a fortune.
The sensors themselves are the cheapest element of the alarm puzzle... so using the old ones doesn't make much sense because it only generates a lot of unnecessary problems.
Replacing such a sensor is also not a task that you will not be able to do on your own.
https://sonoff.tech/products/