You would need to find a bank that allows you to deposit a cheque. There are currently no banks in The Netherlands that offer this service and so far, bunq hasn't publicly shown any interest in adding such functionality. At least personally, I wouldn't get my hopes up for such a feature to be added.
For your current cheque, try to find a bank near you that allows you to deposit cheques. If you live in The Netherlands, that would probably mean you have to look at neighboring countries. There might be some German or Belgian retail banks that allow you to open a bank account. This website provides an overview over banks in different countries: https://www.expatica.com/be/directory/finance/banks/