Unfortunately in Germany almost all banks force you to use an unmodified phone (so no de-Googled) Android as the 2FA. There are other solutions like code generators but they require extra payment.
Buy an older iPhone for ~$150. Install financial apps on it and don't use it for anything else. Keep it in a safe place, only carry it around if you must.
If you need to manage non-trivial amounts of money through your phone, having a specific device to do that is a no-brainer.
Is the risk that someone's going to steal my phone, forcibly hold it to my face, and wire my money somewhere? So far I've known two close friends who got mugged, the robber didn't think of this. Last time I tried intentionally wiring a large amount of money to someone, it took forever and involved tons of approval.
It's common in London, phones are being stolen for the access to financial accounts, not the value of the phone itself. They steal the phone out of your hands while it is unlocked. For example: