I have some experience with house wiring, and more recently gained some experience with 5mm RGB LEDs and an Ardiuno.
In that, I learned about PWM for dimming an LED.
I suspect that the standard wall dimmer an electrician installs is just a variable resistor. I could understand that doing weird stuff if there is some transformer or something in the non-dimmable led lamp.
I found that you can get solid state relays for an Ardiuno that can handle 250V AC and 2 amps. Since they are solid state, I suspect I could turn them on and off fast.
What happens if I PWM a standard "non-dimmable" LED lamp? Is there some complicated circuitry (that I don't yet understand or know of) that will interact poorly with a PWM power source?
(That does bring me to realize that for the PWM to work well, it should operate at a speed that doesn't have any weird "Lowest Common Multiple" effects with the AC supply that would be visible).