Searx is half of it where it calls out to other searches but does not provide its own index as far as I can see. It also does not remix the results.
For me it made more of an enterprise-grade use case (e.g. for building a search for your own file servers or confluence) so I only tested it out a little. It's a huge java project, that's why I decided to go with searx back then...cause yacy was pretty hard to setup.