The 8" iPad mini has 2048-by-1536 resolution at 326 pixels per inch screen. . . and sells for $399. Much faster and much better in color and resolution. Better cameras, video, all around. Not the iPad Pro, but less expensive and smaller. Just about the same weight as your Amazon, but with all metal body instead of plastic.
Update on the 7” Amazon Kindle Fire battery life. One reviewer claims that with a software update he found he could get over 9 hours of use out of it. Not too shabby. He did not say what brightness settings or what use he was putting it to get that battery time.