I'm the creator of Insomnia and I'd love to hear your feedback if you try it out! I'm still a novice to GraphQL, so I'd like to make sure that it accommodates all use cases.
Cool. Insomnia is quite good. I prefer it over Paw (for MacOS only) because it is cross platform and I only want to learn one tool that works on both Mac and Linux.
Lots, actually. Since Insomnia is a full-featured HTTP testing tool, you can use all other Insomnia features with GraphQL like setting custom headers, filtering responses with JSONPath, Nunjucks templating, etc.
~ Gregory