Together with the Philips Hue Gateway it works. This can be used with IKEA Tradfri and of course with all Hue switches.

I have now received the switch, two pieces of information about it:

I could not get the switch to work with IKEA (example start-up with Hue Bridge v2: https://www.youtube.com/watch). Even testing with 10s hold and button combinations did not lead to the goal. In addition, you can see in the video that it also needs app support to assign the functions - a great pity.

Further still important. The Feller box offered here cannot be used as a replacement for a removed flush-mounted push-button. For this purpose, you can buy another version in a specialist shop or from the competition a small plastic strap with 4 screws (electrical material for device mounting Feller Smart Light Control Switch) for CHF 3.95..

This is a very good question. I personally use "FHEM" on a Raspberry as a backbone system and I can link everything via it. You could also set up an ioBroker, which supports Zigbee and Tradfri, at least as far as I know.

But in general I would also be interested in this. According to the internet, Zigbee and Hue should still be compatible "at the moment". That's why I assume that the buttons will work.

As I only have Philipps Hue lamps, I cannot confirm whether the switch also works with other systems. With the Hue system so far without any flaws.