I'm looking for a scheduling client with Bancontact support, since it's by far the most used payment method in Belgium.

CozyCal seems to be the only one close to supporting this, since you guys use Stripe Checkout pages. Is it possible to include Bancontact for payments?

I think supporting iDEAL (https://cozycal.canny.io/feature-requests/p/support-ideal-payments) will be very similar, so it might be worthwhile to investigate passing a custom configuration to Stripe Checkout.