It would be really nice to be able to have types for inputs and results for graphql-client and it feels like it just requires gluing together some existing pieces of code.
A file of graphql queries can be parsed into a Document with GraphQL.parse.
https://github.com/rmosolgo/graphql-ruby/blob/a08c86f097395e27272fdead5037d7b3ef03401e/lib/graphql.rb#L45
And then the tapioca graphq_type_helper can be used to map the graphql types to sorbet types.
https://github.com/Shopify/tapioca/blob/main/lib/tapioca/dsl/helpers/graphql_type_helper.rb
And then you'd want to produce an rbi file that will provide types for the queries produced by GraphQL::Client#parse to be used with GraphQL::Client#query.