Before Amazon introduced this new feature, you’d have to jailbreak your Kindle to use book covers as lock screen wallpapers. In fact, it was one of the biggest motivators for Kindle owners to jailbreak their devices.
The new Show Cover feature works with “most books, magazines, comics, and Manga” according to Amazon.
Currently, the feature works on a select few Kindle devices without ads. These include the Kindle (8th, 10th generation), Kindle Paperwhite (7th, 10th generation), Kindle Oasis (8th, 9th, 10th generation), and Kindle Voyage (7th generation).
If you don’t know which Kindle E-Reader you own, you can identify it here. If you own a Kindle device that supports ads, you can have them disabled for $20 (or calling customer support and asking nicely, according to some reports).
On a supported Kindle device that’s also running the latest Kindle firmware, the Show Cover feature can be enabled by going to Settings > Device Options, and turning the Show Cover option on.