An e-book is defined here as a digital book that lacks a URL. The format for citing an Ebook via a device is:

Author Last Name, First Name. Title of Book. E-reader device, Publisher, Year of Publication.

Examples:

Garmus, Bonnie. Lessons in Chemistry: A Novel. Kindle, Doubleday, 2022.

Doerr, Anthony. All the Light We Cannot See. Nook, Scribner, 2014.