Michiel π³οΈβπ
Maestro can be used with signature, though only for magnetic stripe transactions in certain approved countries (according to Mastercard Transaction Processing Rules, chapter 3.5 "Maestro Cardholder Verification Requirements")
However, bunq does not make use of the magstripe on their Maestro cards and will automatically decline all magstripe transactions with the Maestro card (AFAIK, and I remember once having read it in their terms and conditions). Thus, they don't need to include a signature field on their cards.