Can I integrate my own SP-based product with KanBo?

KanBo uses AD or AzureAD to authenticate users. If your AD on premise is capable of handling external users i.e. using ADFS then KanBo will support it. Whatever your SharePoint is supporting KanBo does it too. Maybe it is also interesting to you that KanBo can be installed just on SharePoint Foundation that is free of charge.