Not entirely the same in Norway, but the rule as written is roughly translated "Sound signal: A bike should have a bell. Other signalling devices are prohibited".

Doesn't stop me from using an AirZound or digital airhorn. Saved me countless times. Like a bell is heard by a driver blasting their stereo while checking their phone, slowly veering into the cycle lane.

Really? I would have guessed you could argue that it qualifies as „one signal giving device“ since it is one single piece of equipment (ie the horn in a car also has many parts, but it‘s presumably fine) and also that it „only produces one constant sound“, where that sound is composed of different frequencies (again, car horns probably don‘t have a pure tone in Denmark either, right?).

Non of those laws are enforced, ever. Even if you get stopped by police. When have you last seen a bike with all the mandetory reflectors?