My bank app refuses to work on LineageOS, but I can use the web interface just fine which has the exact same UI and functionality as the app. In both the native app and the web app I have to authorize any transactions using my national ID, which for me is a hardware token (the app for my national ID also refuses to run). Why is it somehow insecure to initiate this flow from a native app on LineageOS while it is not insecure to do the exact same via a browser on LineageOS? If the app can be compromised, so can the browser - the bank cannot trust all its browser based clients anyway.

The web app has been running with this security model for decades on PCs, and it has been fine. The whole narrative about remote attestation being necessary to protect users is an evil lie in my opinion, but it is an effective lie which has convinced even knowledgeable IT professionals that taking away device ownership from users is somehow justified.