Congrats on the interviews!
Have you worked in this field before? Done clinicals in this area? Gone to conferences? Done CME on the topic? These all show interest.
Other ways: discuss how you plan to advocate for the pt as with a specialty practice, you will probably not be the only provider the pt has (I work nephrology so my pts have several providers too).
What extra coursework do you plan to do to further educate yourself in endocrinology? Will you be mainly dealing with diabetes or the whole spectrum? In my area, the diabetic center is managed by an NP who is very well known in our area for her expertise and ability to handle even the most difficult pts.
Good luck and let us know how it works out.