This way works from Martijn, although I could not use a push button in the intermediate switch, I used a shelly 3i instead.
Hope this helps.
The Dimmer2 works exactly as the Dimmer1 in regards to the wiring scheme, so please have a look at:
https://smarthome-forum.eu/index.php?attachment/12835-ar768-kreuzschaltung-png/ 285 <- three way switch
https://smarthome-forum.eu/lexikon/index.php?entry/113-connection-diagrams-shelly-dimmer/ 169 for more wiring diagrams.