Man are you lucky today. The GitHub GraphQL Explorer had one of my test queries from 2017 stored in my localstorage.

{
  repository (owner: "bolt", name: "bolt") {
    name
    issues (last: 5, before: "Y3Vyc29yOjIxMDI0NDc1NA==") {
      totalCount
      edges {cursor}
      nodes {
        number
        title
        comments (first: 5) {
          edges {cursor}
          nodes {
            body
          }
        }
      }
    }
  }
}

the edges {cursor} is important because they give you the IDs for the before and after params.
As you can see in the query, I get some issues and then its comments. But the comments are also limited to a specific number so you have pagination there too.
(and comments have reactions (paginated) and issues have actions (opened, closed, etc. ) (paginated too)). It really is a mess if you want to grab everything