My mom just bought a nook and B&N had a large number of free books to download. She is technically challenged being 76 years old, so I set it up and have been helping her learn to use it. I just got my libre and am learning it as well.
I have the Libre Pro and the free books from B&N are in ade epub format. So I made a folder on my sd card for the libre and named it B&N books. I transferred the files downloaded into my documents folder on my pc called "my barns and noble ebooks". It will have a folder under your email address for whatever B&N account is listed. My B&N folder has 2 folders- my mother's email and my e-mail. I copied these epub files(NON DRM) onto my libre sd card and they open on the libre.
So in answer to your question- yes- B&N epub files will work on your libre pro. I haven't tried any drm'd files since all the books I have are the free ones. B&N have 75 or more free books available for their nook listed on the left column under free ebooks. But you have to have an account and give a credit card to keep on file- even for the free ones.
I'll bet if you remove the drm they should work on the libre too. When I buy a book for the Nook I'll give it a try and post results.