Photos: https://photos.app.goo.gl/JBW4wv51Eb6RX1ej8 

Contents: [Dobrica Pavlinušić's random unstructured stuff]
• Dobrica Pavlinušić's random unstructured stuff (Board markings) 
• Dobrica Pavlinušić's random unstructured stuff (wifi module) 
• Dobrica Pavlinušić's random unstructured stuff (sonoff tasmota) 
• Dobrica Pavlinušić's random unstructured stuff (enable user config) 
• Dobrica Pavlinušić's random unstructured stuff (build) 
• Dobrica Pavlinušić's random unstructured stuff (flashing) 
• Dobrica Pavlinušić's random unstructured stuff (erase flash) 
• Dobrica Pavlinušić's random unstructured stuff (write_flash) 
• Dobrica Pavlinušić's random unstructured stuff (first powerup) 

Board markings
PLD‑PZ005‑V1.9.
 12/13/2018
wifi module

TYWE2S
pins on flat side (bottom)
3v3
 gnd
 rx
 tx
 12
 14
pins on side with components
rst
 ad
 13
 04
 05
sonoff tasmota
https://github.com/arendst/Sonoff‑Tasmota/issues/3950 
{"NAME":"Teckin","GPIO":[0,17,0,53,134,132,0,0,131,56,21,0,0],"FLAG":0,"BASE":52}

enable user config
dpavlin@nuc:/nuc/esp8266/Sonoff-Tasmota$ git diff
diff --git a/platformio.ini b/platformio.ini
index 59fab723..98d285fc 100755
--- a/platformio.ini
+++ b/platformio.ini
@@ -193,7 +193,7 @@ build_flags               = ${core_active.build_flags}
 ;                            -DFIRMWARE_BASIC
 ;                            -DFIRMWARE_KNX_NO_EMULATION
 ;                            -DFIRMWARE_DISPLAYS
-;                            -DUSE_CONFIG_OVERRIDE
+                            -DUSE_CONFIG_OVERRIDE
 
 ; *** Fix espressif8266@1.7.0 induced undesired all warnings
 build_unflags             = -Wall

dpavlin@nuc:/nuc/esp8266/Sonoff-Tasmota$ vi sonoff/user_config_override.h

Configure defaults for your device and build only sonoff firmware (we don't need all variants)
build
dpavlin@nuc:/nuc/esp8266/Sonoff-Tasmota$ platformio run -e sonoff

flashing
connect IO0 to GND to get in bootloader
erase flash
Flashing sonoff doesn't work for me reliably if I don't erase flash first. I suspect that config area is corrupted or something similar.
dpavlin@x200:/mnt/nuc/esp8266/esptool$ ./esptool.py --port /dev/ttyUSB2 erase_flash                                    
esptool.py v2.8-dev
Serial port /dev/ttyUSB2
Connecting....
Detecting chip type... ESP8266
Chip is ESP8285
Features: WiFi, Embedded Flash
Crystal is 26MHz
MAC: c4:4f:33:87:b1:bd
Uploading stub...
Running stub...
Stub running...
Erasing flash (this may take a while)...
Chip erase completed successfully in 6.6s
Hard resetting via RTS pin...

write_flash
dpavlin@x200:/mnt/nuc/esp8266/esptool$ ./esptool.py --port /dev/ttyUSB2 write_flash 0x0 ../Sonoff-Tasmota/.pioenvs/sonoff/firmware.bin 
esptool.py v2.8-dev
Serial port /dev/ttyUSB2
Connecting....
Detecting chip type... ESP8266
Chip is ESP8285
Features: WiFi, Embedded Flash
Crystal is 26MHz
MAC: dc:4f:22:ee:a2:4a
Uploading stub...
Running stub...
Stub running...
Configuring flash size...
Auto-detected Flash size: 1MB
Compressed 565472 bytes to 388329...
Wrote 565472 bytes (388329 compressed) at 0x00000000 in 34.3 seconds (effective 131.8 kbit/s)...
Hash of data verified.

Leaving...
Hard resetting via RTS pin...

Please note that 565472 is bigger than 512Kb which means that OTA update won't fit if firmware size isn't reduced.
dpavlin@x200:/mnt/nuc/esp8266/esptool$ ./esptool.py --port /dev/ttyUSB2 write_flash 0x0 ../Sonoff-Tasmota/.pioenvs/sonoff/firmware.bin
esptool.py v2.8-dev
Serial port /dev/ttyUSB2
Connecting....
Detecting chip type... ESP8266
Chip is ESP8285
Features: WiFi, Embedded Flash
Crystal is 26MHz
MAC: c4:4f:33:87:b1:bd
Uploading stub...
Running stub...
Stub running...
Configuring flash size...
Auto-detected Flash size: 1MB
Compressed 491040 bytes to 339235...
Wrote 491040 bytes (339235 compressed) at 0x00000000 in 30.0 seconds (effective 131.0 kbit/s)...
Hash of data verified.

Leaving...
Hard resetting via RTS pin...

Remove bridge from IO0 to GND and test module.
first powerup
open web, toggle relay
verify that voltage seems sane
Wifi > Hostname
Mqtt > Topic
other > friendly name (displayed on web UI)
Logging parameters > Telemetry period ‑ 10 # report sensor status every 10 sec
open console, and read voltage at output:
18:09:28 CMD: VoltageSet 233.9
18:09:28 MQT: stat/lemilica/RESULT = {"VoltageSetCal":1724}