So I bought some DS102 switches (no touch, with physical buttons, EU) that @tyjtyj already mentioned above. Unfortunately, tuya-convert appears not to work, so I will have to try and flash them the old-fashioned-way. Here are some pictures:
As you can see, there is a small board on top with the ESP8266 (TYWE3S) on it. GND and 3.3V are easily accessible from the socket on the bottom. TX and RX are on the bottom-right of the chip on the pic above. No sockets, but should be easy enough to wire.
I will report back on my success (hopefully) when I find the time.