My bank offers both an app and a website which is nice, but the app is mandatory for doing any kind of operation involving money (which is not that uncommon when logged-in in your bank accounts ;) even when connecting through their website, as the app is used for some ID-ing process.

Then, there are a few not-mandatory but such-an-effing-pain-to-not-use apps, say to ID oneself with some (public) services.

I use a dumbed down iPhone (like, really: no social, no games, no whatever not even email is configured on it) just so I can access those few apps.

Mine does but there's 2fa using a dedicated app. Although a 2fa machine is available and sent out also.

My bank warned that they are planning to phase out the code booklet and replace it with a mobile app. Sure, you can continue to use a web browser, but how do you verify anything without a mobile app?

Also, some apps are very picky and refuse to work properly unless your android has GAPPS and is in the in an unmodified state just like the OEM intended. That’s bad news for privacy oriented Android users, let alone anyone who wants to run something even more FOSS.

Don’t other people’s banks have web portals?

Sadly, some finance services are app only, app-that-don't-run-without-Play-Store only.

Where I live, cashless payments via NFC. But I have the option of using a plastic card too.

Why "other than depositing a check remotely"? Depositing a check remotely is the reason I have to use my bank's mobile app.