Which API should be used to query all the linked instances(through edges) based on a root node

type SimulationModel {
  modelName: String!
  nodes: [SimNode]
}

type SimNode {
  modelName: String
  input: [Key]
}

type Key{
  modelName: String
  unit: String
}

With the above sample schema, I am able to fetch all the SimNodes together with their Keys for a specified SimulationModel instance using the GraphQL:

query MyQuery{
  listSimulationModel(filter:{externalId: {eq : "00000000-0000-0000-0000-000000000000"}}){
    items {
      externalId
      modelName
      nodes(first:100){
        items{
          externalId
          modelName
          input{
            items{
              externalId
              modelName
              unit
            }
          }

        }
      }
    }
  }
}

How to do do the same with the APIs, could you give an example? Not sure which API should be used(instances/list, instances/byids, instances/search, instances/query).