A blank superbook is supported on all devices and all desktops (all viewports & operating systems) with a modern browser.
It is only the content that could limit the outreach of your book. For example, webgl may not be supported on some older devices and desktops. If your book uses webgl, then it will not be available on those devices.
Always test your content thoroughly using multiple devices. Use responsive typography for text and images, else you'll risk supporting fewer devices than you could.
Pro tip: Provide support information on the cover page of your book. Refer caniuse for HTML5 & CSS3 support and coverage.