PetraCan you buy 'smart' plugs that don't connect to the Internet, but only wireless & batteryless buttons like the ones they have on buses these days?
C.Yes, there are tons of the things that use the 433 MHz (or 3xx MHz) remotes. Many are programmable, so you can use remotes of your choice - multi-button pocket fobs, ones you stick on a desk or the wall, ones that mount on the wall and look like a normal lightswitch, etc.
They're cheap, so the big brands don't do them - they want to sell you the connected type (and probably a subscription), but you can find them on your local cheap & cheerful Chinese tat site.
If you're familiar with Big Clive, he's done a bunch of videos on these types of things - how to use them, teardowns, autopsies of dead units, etc. You can try searching his (large) back catalog with something like:
