How do A2A bank transfers (Nordea Solo, OP-Bank) work in Magento?

Account-to-account (A2A) bank transfers are Finland’s #1 online payment type, ~50% of all online payments. The flow is unique to the Nordics:

1. Customer selects their bank at checkout (e.g. Nordea Solo, OP-Bank, Aktia, S-Pankki, Säästöpankki).
2. Magento redirects them to their bank’s payment page (an embedded form, e-banking session).
3. Customer authenticates with a mobile bank ID (Mobiilivarmenne / OP Mobiiliavain / Nordea ID), same UX as logging into their bank app.
4. Bank confirms the transfer in real-time, returns customer to Magento with a success token.
5. Magento captures payment, generates order + Finvoice 3.0 invoice (for B2B).

Why so popular? Lower fees than cards (~0.5% vs 1.4%), instant confirmation (Finland has had real-time interbank rails for 20+ years), no chargeback risk, and customers trust their bank more than a card form. We wire it up via Paytrail (one module, all banks) or direct bank APIs (Nordea Open Banking, OP API) for enterprise volumes where fee negotiation matters.