>Girocard charges a 0,3% fee vs visa/mastercard 3%

AFAIK all credit cards in the EU have similarly low interchange rates because of EU regulation.

0.2%

> Payment service providers shall not offer or request a per transaction interchange fee of more than 0,2 % of the value of the transaction for any debit card transaction.

https://eur-lex.europa.eu/eli/reg/2015/751/oj/eng