Most intercoms I've seen don't need any soldering, you'll usually hook into the existing screw terminals of the intercom unit inside your apartment. The Nuki software comes with wiring "recipes" for many popular intercom models and tells you what to hook where. Sometimes your model isn't recognized so you have to get creative, but nothing crazy. Analog intercoms are easy, at worst you hook in just the wires that trigger the "button push", maybe even the one that detects when the intercom rings and gives you a notification.

But it also supports more complicated setups like digital intercoms where it will hook on the bus and learn the various codes that are sent for different operations, or enable the voice function through the phone app.

The biggest benefit is that if your intercom is compatible, it just works. It's the convenience, not that you can't get the same with a janky solution with enough elbow grease. No need to tinker with the firmware, the batteries last forever, and even in the most basic setup you'll have a few more advanced features.