GUWonder

Coffee shops often have restrooms that don't require payment to access the restrooms. This may or may not require buying something and/or getting a bathroom access code, but the larger and busier the coffee shop in this region and the further away it is from a major public transit hub, the easier it will be to use such restrooms without having to pull out coins.

Also, malls and large department stores are more likely to have free restrooms for customers/potential customers.

There are probably some apps that list where the free restrooms are around in some of the cities on such itineraries. It's rare that I find a restroom in the Nordic area where bank card or contactless payment options are an option, and in this regard Norway is more an exception than Sweden and Denmark.