Lazyweb: I have local servers that have HTTP(s) endpoints for doing Special Events.
What's the easiest way to get a physical button that I can stick some batteries into, and it'll trigger that HTTP call (over the wifi) when I push the button?

@foone

Most of the things that were good for that have vanished from the cheap places.

I should have bought so many more WiFi mains switches when Poundland* was filled with them . . .

*Those were not £1. They were £5 but it wasn't bad for an easily co-opted, mains powered Tuya ESP microcontroller module with a relay to switch mains current, all packaged in a nice inline case to fit any appliance.