If a priest was writing a book about healing brought forth by confession could you give him permission to write what you have confessed to him? Is he still bound by the seal of confession if you the penitent want it to be public knowledge?
As far as I’m aware, the seal of the confessional holds for any scenario imaginable - I imagine this includes the penitent giving the priest permission to divulge what was said. So no, I don’t think the priest could reveal what was said.
No. He’s still bound. You can write what you want yourself about your own confession and have it be your own work. But he can’t write about your confession.
If you told him about it again outside of the confessional he probably could