Thanks Gilles
That is excellent. However I already have lots of ESP32 and the later versions.
If I am considering, for example, a light switch modification to a 'smart unit' with wifi then take a look here (you can use google translate on the page)
https://mauser.pt/catalog/pesquisa.php? ... words=tuya
this is just a small selection of the Tuya integrated devices which all coexist with the home assistant app on PI 4.
As you can probably see, the price is so low that it is not worth considering adding the 220v mains reduction circuit, the relays and the protection and casing to the esp32 at these prices.
If you look on aliexpress, they are even cheaper. I can also use virtually ANY smart device - sonoff - and indeed MQTT protocols with the home assistant program. I love building stuff, but I simply cannot build at these prices so far easier to buy
Joe