PS-16-DZ Dimmer~
The PS-16-DZ dimmer uses eWeLink app same as Sonoff devices. It's available from Amazon and Aliexpress. It may under different name, but the model number is PS-16-DZ.
Pics~
Opened it up, found an ESP8285 and a Nuvoton N76E003. 
Flash and GPIO pins~
Remove the ESP8285 daughter card DLX-MKCK01 from the main board and flash Tasmota.
pin1 RST -> N76E003 P0.5/PWM2
pin2 TXD -> N76E003 P0.7/RXD
pin3 RXD -> N76E003 P0.6/TXD
pin4 GPIO13/MTCK -> LED
pin5 3.3V
pin6 GND
Communication between ESP8285 and N76E003~
It uses AT command to communicate between ESP8285 and N76E003 over UART at 19200 baud.
Turn on the switch from ESP8266:
Send from ESP8266
AT+UPDATE="sequence":"1528335040032","switch":"on"
Receive from MCU
AT+RESULT="sequence":1528335040032"
Send from ESP8266:
AT+SEND=ok
After 0.7s
Receive from MCU
AT+UPDATE="switch":"on","bright":44
Send from ESP8266:
AT+SEND=ok
Turn off the switch from ESP8266:
Send from ESP8266
AT+UPDATE="sequence":"1528335118327","switch":"off"
Receive from MCU
AT+RESULT="sequence":1528335118327"
Send from ESP8266:
AT+SEND=ok
After 0.7s
Receive from MCU
AT+UPDATE="switch":"on","bright":44
Send from ESP8266:
AT+SEND=ok
Change brightness to 44 from ESP8266:
Send from ESP8266:
AT+UPDATE="sequence":"1528335181502","bright":44
Receive from MCU
AT+RESULT="sequence":1528335181502"
Send from ESP8266:
AT+SEND=ok
After 0.7s
Receive from MCU
AT+UPDATE="switch":"on","bright":44
Send from ESP8266:
AT+SEND=ok
Turn on the switch with faceplate button:
Received from MCU
AT+UPDATE="switch":"on","bright":44
Send from ESP8266:
AT+SEND=ok
Turn off the switch with faceplate button:
Received from MCU
AT+UPDATE="switch":"off","bright":44
Send from ESP8266:
AT+SEND=ok
Change the brightness to 52 with faceplate button:
Received from MCU
AT+UPDATE="switch":"on","bright":52
Send from ESP8266:
AT+SEND=ok
Holding the middle button on faceplate to reset the device:
Received from MCU
AT+SETTING=enterESPTOUCH
Send from ESP8266:
AT+SETTING=enterESPTOUCH