The status quo sucks. Political solutions are probably years off, and likely entail making Apple and Google behave rather than mandate open standards and allow alternatives. We are stuck with this duopoly for now. (At least desktop and laptop computers don't suffer from this.)
Alternative OSes on the smartphone are pointless if participating in digital society is your goal, because your friends and family will all use WhatsApp or something (this varies by country), and your bank will make banking with them harder if you don't use their app. Your government will increasingly rely on you owning a smartphone for digital access. In the Netherlands, digital access to healthcare records now by law requires that you either use the DigiD app on Android or IOS, or that you resort to begging for a paper copy; there will be nothing in between¹. When travelling, the apps for the larger public transport companies will have all the delays, re-routings, e-tickets, and other useful stuff. All of these require one of the two smartphone software stores, Apple's or Google's.
At least with GrapheneOS you can limit the Play Store to that handful of apps you must grudgingly use. The rest can be gotten from the, excellent, FOSS F-Droid store (like OsmAnd~, OpenCamera, and OrganicMaps), so you can minimize having to deal with the noise and chaos of the Play Store.
The Swish-thing sounds totally dystopic by the way. It's just by a quirk of fate that we don't have that trend in the Netherlands, where paying with a debit card is standard and smartphone payment systems basically just use that same system with a digital debit card. The war on cash is being waged here too though.
1: Use of DigiD, the Dutch digital identity system, without the app is not allowed for healthcare records, and existing healthcare systems are required to migrate to this. It is still allowed to login for other purposes like taxes using a password or SMS confirmation — for now.