For DynamoDB specifically, ScyllaDB had a Dynamodb compatible mode. There are several options (open source and otherwise) with s3 compatible APIs. I think it is

For DynamoDB specifically, ScyllaDB had a Dynamodb compatible mode. There are several options (open source and otherwise) with s3 compatible APIs. I think it is more likely we'll end up with replacements for individual services and maybe at some point it will be possible to glue them together as a replacement for a significant subset of AWS