I too am interested in this. I would go a step further than @Vivien-Grey-Quokka though, and would like to be able to auto save to any account, not just saving goals.
The use case here is that people just want to set aside some money without a particular goal in mind.
In my mind, the requirement for a saving goal when you set up auto save actually makes little sense. Since bunq is the Bank of Freedom, why restrict people to a saving goal? Why not transfer the money to any account in your bunq membership, or even to your child's college fund in some other place?