I am set up with my books here: https://www.authorgraph.com/authors/amsaph
You'll find a widget on my website and blog sidebar as an ever-present quick link to that page. It looks like this:
If your favorite author isn't there, I believe there's a way to suggest it, or you can find that author's webpage and contact them through it to suggest it.
Who says you can only sign print books? Where there's a will, someone will find a way! Ebooks are real books, just in pixels instead of dead trees.