You know how HTTP GET requests are meant to be idempotent? Well, do I have the story for you ... a while back I added WiFi control to our garage doors with little Wemos D1s.
The Wemos expose a simple web page with a link that says "Toggle". The endpoint for the link activates a relay, which is hooked up to the push-button on the garage door, which makes the door raise/lower/halt.
(This /toggle endpoint responds to GET requests. I threw the code together in minutes and was too lazy to spend another couple minutes figuring out POST. #regret)