API Federation requirements

Hello, community.

I have been researching Apollo’s approach to API Federation and I got a question about bringing plain REST APIs to the federated graph. Say I have 100 REST APIs today. Do I need to rewrite every single one of my APIs to somehow “transform” them into a GraphQL API, or is there some sort of “graphql wrapper” or “proxy”, that I could use to quickly “convert” the REST APIs into a GraphQL subgraph, and only then, be able to add it to the federated supergraph?

Thank you in advance.