Yes, of course, they'd have to provide a port on day 1, or people would not use that mobile OS. It's the same thing if the mobile OS lacked, say, Mobile BankID

Yes, of course, they'd have to provide a port on day 1, or people would not use that mobile OS. It's the same thing if the mobile OS lacked, say, Mobile BankID (a 2FA app used for a lot of things in Sweden). Those are simply hygiene features, like a web browser. It's common for a new product rollout (whatever it is) to have discussions with different companies beforehand, this is how e.g. games magically appear on the market around the same time when a new game console is launched. The game studios get their hands on development hardware and documentation before anyone else. So I don't see Swish being any kind of blocker for anyone wanting to roll out a new mobile OS in Sweden. Whoever wants to come in first contacts Swish, they do the legal paperwork and then contract someone to build the app. And it's not like Swish is the only option to pay in stores. It's not that common, in fact. Paying with a debit card is the most common thing.