The HomeEasy switches I picked up are 433mhz RF remote control dimmer switches. They come with these instructions in the packaging which shows how to wire them up:

They have a little blue LED on the "touch" part of the switch which is on when the light is off and is off when the light is on.

I can't tell you how the dimmer switch part works internally or how the 433mhz transmitter circuit has been built but I'm guessing it must work like other regular dimmer switches where there's some circuitry to chop up the AC into a DC voltage to keep the 433mhz transmitter always on and to power the LED. If I had to guess it's probably something like this:

To be completely honest imo these are not the optimal solution because switching them on and off remotely via 433mhz is basically a "fire and forget" operation. This means that if they're switched at the wall, the remote system has no knowledge about that manual switch action because these type of switches only contain an RF receiver; there's no RF transmitter or anything else that might be able to notify of state change.

I've not used any other similar RF switches like the many available on aliexpress / bangood but I assume these would work the same way. I guess the advantage with the HomeEasy stuff is that it was once-upon-a-time manufactured in the UK and these HE switches really do fit UK type switch boxes (25mm deep).

For me, in the absence of anything else, this is a semi decent solution for now but I'd much prefer something like a hackable WiFi sonoff switch.