I am using the device in a Home Assistant setup, so I wanted to flash Sonoff-Tasmota on it.
The non-DAC version should probably be supported out of the box, by using the "Generic Device"
I ordered the version with the DAC, so that was a bit more difficult to get running.

I implemented a first try at:
https://github.com/arendst/Sonoff-Tasmota/pull/3015

This enables dimming with the DAC using the Tasmota firmware, MQTT and webinterface.

Using the ESP + i2c DAC combo, getting fast and *clean* results when used as a light dimmer, even with the ESP8266 busy irregularly (running complex servers on the chip: web, udp osc, UI, ...).
Documentation needs some improvement, diagrams missing, but other then that - it's a safe and well done product !

I wanted an ESP device which could dim my lights and this is exactly what I needed. Not suitable for the halogen lights I have, but it's time to replace those by LED lights. In my test environment it's working flawlessly. I bought 2 and all was packaged very good and it arrived rather shortly after ordered. Communication (I had some....a lot of questions....) was very good and also fast. Great stuff, great support !!

After playing around with just on and off switches with GPIO or serial on a Raspberry PI, it was time to work with dimming hardware. And surprisingly there is not so much to find. Till I found this dimmer and love it!

It is small in dimensions. So I could just integrate next to my GPIO switches.
It can just control 220V devices (I use a bulb light for heating). So by playing around with some code I could adjust the temperature by dimming the light.
It comes with a fuse, which to is an extra assurance that I can not overload it. Nice!

And it integrates that easy with a Pi and Python, that I support this device with my TerrariumPI software for running a terrarium fully automated https://github.com/theyosh/TerrariumPI

There are some downsides. First my problems is that the shipping costs are higher then the device itself. I just ordered a bunch, but the shipping costs are a bit high comparing with the cheap price for this device.
And I get the feeling that the dimmer effect from 60% and higher are not really noticeable. At least I can't see it at my light bulb. From 60% till 100% looks the same.

But overall, I would advise it to other people if they are looking for a dimmer module for a Raspberry PI

I was looking hard for a solution to digitally (=PWM) dim my high-voltage lamps, tried out a few solutions, paid far more for so called ready-to-use products but wasn't satisfied at all.
The two MPDM boards I got convinced me of the thought-out design - PCB is well layouted, mains are very well separated from the low-voltage part.
I connected them to Sonoff devices - having an ESP8266 inside - and drive them via its PWM channels.
Result looks like this: https://imgur.com/a/xhkar
Working like a charm!

The only thing to consider is, to not reach the maximum PWM / voltage input level, otherwise lights start flickering and some other undefined things might happen.
For the ESP that's a value around ~910 (of 1024) - between that and 0 everything is working perfectly fine.

EDIT: I almost forgot to mention the awesome support from the developer/seller. That was very helpful, communication was very friendly and faster than expected (meaning, he had to wait for my replies instead of me waiting for him :))