[hyghjiyhu]

A solution could be having a tiny non-rooted Android system as a "coprocessor".

[ExpertAdvisor01]

This won't work. The tiny non-rooted system wouldn't get certified by Google and therefore not pass hardware attestation, which most banking apps use.

[hyghjiyhu]

Well you could take a certified system off-the-shelf and integrate it into a bigger thing.

[NoGravitas]

I think they mean having a second non-rooted phone that is certified but cheap.