The first step to being able to accept 3DS2 payment is setting up a SetupIntent/PaymentMethod.
It is in progress in https://github.com/3scale/porta/pull/2308 and there are details to polish.

In this implementation, we are using Stripe gem to create the customer/setupIntent, and the activemerchant gem to 'charge' the customer. But we are not fixing the implementation when the bank requires an extra authorization step