Banking establishment should take note. They often over-complicate things and rely on "security through obscurity". Monzo opening up their security architecture and even some of their source code puts them to shame. I really like the air gap Notebook and custom OS on CD-R and their ceremonies. It looks like they got very competent people to think it through properly.

Source: formerly at one of the largest banks.

I hope air gaping will stay a niche. If it goes mainstream there will be more attacks on it...