I went to Hornbach store behind my house and ended up buying a simple cheap LED dimmer (8 EUR) with remote control. The issue with it was, that it is a DYI component, which connects on the cable in between the power source and the lamps. So I would either have to cut the cables of the original power sources delivered with the lights, or buy a new 24V power source.
The dimmer is a simple device, which allows to set the intensity of the LED lights in about 6 steps. The downside is that there is no possibility of scheduling. So I use one lamp with the original scheduler from the lamps manufacturer and the other lamp I operate manually with this remote operated dimmer.