{"NAME":"2 Gang Switch","GPIO":[158,57,0,17,22,18,0,0,0,21,56,0,0],"FLAG":0,"BASE":18}

Smatrul appears to be the main seller but they are also sold by Avatto (I can confirm that even 99% of the packaging is the same). Tuya convert was attempted and did not work.

Ground GPIO0 during boot. Ground RST as well. (So really that means a 3 pin splitter from GND to GPIO0 + RST + GND of Serial Flasher.)

After clicking “Start” in Tasmotizer, wait 1 second, then UN-ground RST and it will finish the operation. Or make a momentary connection just before flashing starts?

I watched the red lights of TX/RX on the Flasher, after clicking “Start” they will flash a few times, then stop briefly. This is the best time to un-ground RST. If it doesn’t go bright red right away, try making a momentary connection. Multiple attempts may be needed.

The 4 Gang version of this may lack a solder point to the RST pin. A momentary connection during the flashing process may be enough.

It may not be necessary to do all this extra work. Try doing a simple 4 pin flash first.