Homekit firmware for Sonoff mini
You can wire a switch across S1 & S2, this is NOT 240V, it is only ESP8265 signal level and does not require a paticularly heavy gauge of wire.
Tested in UK dry linning wall box, tight fit but works ok.
12th April 2022 - New capability added to preserve the power state over a power outage. By default the state will not be preserved, if you want to change the default to preserve the state then using Eve app set "Preserve State" to "On".