While this article teaches you how to transfer files securely, you should only transfer .epub files you have legally purchased. If you bought the book on Amazon and want to strip the DRM to read it on a Kobo (your legal right in many jurisdictions under "fair use"), tools like Calibre (free software) are the solution.
Starting your day with a savory breakfast instead of a sugary one prevents a "glucose roller coaster" for the rest of the day. While this article teaches you how to transfer
If you are transferring the book to yourself between devices, internet clouds are stupid. Use local hardware. but their offers a free tier.
Glucose Revolution: The Life-Changing Power of Balancing Your Blood Sugar While this article teaches you how to transfer
Most people know Proton for email, but their offers a free tier.