So, your answer is no, you can’t build one. Nor is your Kindle capable of doing what an iPad does.
Go right ahead paying yourself nothing an hour to tweak around with computer parts. Everyone needs a hobby. I’ve got better things to do with my time than cobble up homebrew computers.
My kindle is built to let me read books, it does that, indoors, or outdoors. I don’t have to keep paying for it to be connected to the web. I can download hundreds of newspapers or magazines for free, plus any number of books.
As for building my own machine, it keeps my brain going, its nice to have to use your brain when you compute, Apple did a nice job of providing computers for folk that don’t want to think much, but pay more. My “home brew” is cutting edge, I like that. I’ve got better things to do with my money than waste it on dumbed down pieces of trendy glitter.