Kindle question: How do I put public domain books on my kindle?

By Winter40

Amazon used to let you grab a bunch of public domain books for free on their store (stuff like the Bible, Austen, Ivanhoe, that kind of older stuff). Now it seems like they’re charging for them—usually like a buck—or bundling them into Kindle Unlimited. I don’t really want to pay for books that are already free somewhere, so is there a way to get them on my Kindle without using Amazon/without paying?