Things you can't do with the website:

• Login with biometrics. Wants password and 2fa each time. As it should, but it gets tedious, especially when I want to confirm online payments (which need to be confirmed inside the interface after you login).
• No contactless payments. You can enroll a card into Google Pay but fuck Google, I don't want them seeing what I buy.
• No notifications, hope the bank is willing to send SMS instead.
• Bit more tedious to send money to someone because the website can't look up contacts by name, have to look them up separately and copy the phone number over.

They are important.

I need to use them on the go so it's a must have.

• 2FA
• Some banks I use require I aprove transactions on my phone when I am paying this online
• One bank I use has tap to pay on the app instead of relying on Google Wallet

I live in the Netherlands, where there's a QR-code-based payment method called iDeal, which you need a Dutch banking app or little code machine thing to use. With my bank, at least, there are a few things you can do with the website that you can't do with the app, but for day-to-day use the app's fine.

NFC payments

Works fine on lineage os