I would like to offer payment on debit/credit via the POS module for registered partners. I tried different Paymentmethods but found no configuration wich would debit/credit a partner.
Is there a way to do this or a nice API workaround to support such a feature?
Do you mean Credit Card? For 10.0, you can set it up via Electronic Cash in POS App, see detailed explanation here: https://www.odoo.com/forum/help-1/question/authorize-net-payment-logic-84953