Many banks don't provide HTTP endpoints (except for business versions). My bank, Monzo, does not. My other bank TSB does provide a website, but it's awful.
Wait, you have to use a smartphone app to interact with your bank? There is no website with 95% of the functionality (or bonus functionality that the app doesn't have) available as a website for desktop users?
This is rather unusual, the credit union I use in the USA offers an iOS and Android app that is literally a webview of their mobile website, plus a dash of OCR for check handling. Using the PWA is nearly identical, it even works on a PinePhone with Maemo or any other operating system that can run a semi-modern browser.
Yup that's pretty much it. To Monzo's credit they seem to make a point to work without Google Play Services, but iOS users would be screwed in the event the App Store was blocked.