BorisArezki Wise (bunq's partner for international transfers) does not support sending money to Cuba. And CurrencyCloud (bunq's partner for local currency accounts) does not offer Cuban Peso accounts. Therefore, you would need to find another third-party that can help you with transferring money to Cuba.
There aren't many offerings out there because of the US sanctions, but there are also some work-around like purchasing prepaid mobile phone credits that the recipient can then resell for cash.