This is an example project of building a single webshop API using GraphQL and ASP.NET Core.
You can play around with GraphQL and this schema by using the prebuilt docker image. You'd need a working docker environment for this.
docker run --rm -i -p 5000:5000 hamster21/graphql-showcase
Point your browser to http://localhost:5000/graphiql/ afterwards to get a visual client to the API.