Also, https://aws.amazon.com/certificate-manager/

It's a very nice feature, but you can't actually get the cert to use on your own servers or devices. You can only use it with AWS services, like their load balancers and Cloudfront. It makes a lot of sense that they do it this way, it makes it very easy to keep secure, since you never get the key. However it doesn't solve the same problems that Let's Encrypt does, and that's ok.