Drewanchel - maybe, but not likely
Dunkelfelger - Myne can't physically survive if she was born there, she said so herself
Both of those duchy are tolerant to commoner, but i don't see any of them sneak out of their duty and go to commoner district to play/entertain themselves like Sylvester. The chance for Myne to actually meet Archduke/Archduke candidate are slim to none. Even if they know her after her successful business, at best they would only sponsor her, not adopt her to the family (probably because she would be older by then and has been baptized), marriage is also out of the question (commoner can't marriage noble, as state by Ferdinand)
Also the point about ditter with Dunkelfelger: Myne only have the chance showcase her ditter ability AFTER being adopt as Archduke candidate and enroll in the Royal Academy. The Dunkelfelger probably won't give her that chance, i mean look at her, a tiny sickly girl who collapses after walking a few steps.