I have a redmi note 4 (mido) and can definitely switch between apps just fine. About banking, since the law in France doesn't require you to have a smartphone (yet?), I pretended I have a dumbphone to my bank, so 2FA is SMS-based for payments, which is not awesome (why not standard TOTP?), but still better than having their crapware in my pocket all the time.

What does 4+2 GB mean? I tried googling Redmi 4+2 GB but it only returns Redmi 4 from 2017 that has only 2GB of ram. Surely that's not what you're talking about?