[elseleigh]

Sailfish OS is a non-duopoly option. There are community builds for a wide range of devices, and official licenses which support a smaller number of devices but include extras including an Android compatibility subsystem so you can run Android apps which don't have Google dependencies (ie, a majority of them). https://sailfishos.org/

Lineage OS offers a Google-free Android operating system that also runs on a wide range of devices. https://lineageos.org/

[dalke]

I understand these exist. However, that doesn't mean BankID or Swish will work on them, or will continue to work with them in the future.

BankID says the risk is entirely mine. That is not a risk I want to take. I figure it's easier stay with what I know works than to backtrack in the future from a temporary technical workaround.

This requires a political solution, not technical one.

That such solutions exist can help inform the political decision. The government could require BankID, etc. to support additional options, and in the interest of national sovereignty could even provide funding for that goal. If the banks require a higher level of security on the servers, the government could provide those servers instead of a non-EU monopolist.