Would it not be a good idea to develop a NPAPI plugin interface for Opera?
It is not trivial to do if you use Aura for your interface, which we do. Chromium for Linux used to have NPAPI support and dropped it when they switched to Aura.
It could be done but it is not worth the effort. All the browsers are now moving away from NPAPI. We will eventually stop support for it on Opera for Windows and Mac as well.
It is Oracle who needs to catch up with the real world. There have already been enough security problems with NPAPI Java, already.
I cannot live with a browser unfit for bank transactions.
That is the funny thing. It tends to be banks doing this despite Java's poor security record. You should encourage your bank to move away from Java. In Norway the BankID system that many banks use relies on Java but it is now being switched over to JavaScript. The hope is that other similar solutions in banks around the world will go the same way. This is a far better outcome than browsers clinging onto NPAPI support for the likes of Java.