Just today, AWS announced a fork of Elasticsearch: Open Distro for Elasticsearch - https://news.ycombinator.com/item?id=19359602
A few months ago, AWS launched a MongoDb fork
A few months ago, AWS launched a MongoDb fork
(There's also https://aws.amazon.com/corretto/ , a long-term-support version of the JDK, because Oracle is getting more aggressive about Oracle JDK licensing.)