Call different service depending on one of field service

Schema Design
,
1

So I have a few services that provide Product data but this services has separate data stores. Is possible to query a specific service depending on field value?

I describe problem with the GQL below.

##
# This is supergraph
##

# Unique ID is `service` and `id` pair. But there is no single service
# that has access to all data to provide this information.
type Product @shareable  @key(fields: "service id")  {
    service: String!  # This can be enum if needed or even could be skipped
    id: String!
    name: String!,
    owner: String!,
}

type RespServiceA @shareable {
    # (...) some other fields
    product: Product!
}

# ServiceA is from service-a subgraph and use different dataset than service-b
type ServiceA {
    # This will always return `A` (the name of service)
    name: String!
    # This should be called only when service = 'A'
    products_by_id(id: String) -> [Product]!

    # now here router has a hard task as there is a `Product` inside `ProductWrapper`
    #     and the Product should be resolved by `ServiceA` or `ServiceB` depending on `Product.service` value
    #
    # in my scenario `RespServiceA.product` will alway be from ServiceA::products_by_id
    complex_query(query_parmeter: String!) -> [RespServiceA]!
}

# ServiceB is from service-b subgraph and use different dataset than service-a
type ServiceB {
    # This will always return `B` (the name of service)
    name: String!
    # This should be called only when service = 'B'
    products_by_id(id: String) -> [Product]!

    # similar `complex_query` as in ServiceA but returns RespServiceB
} 

type Query (
    service_a: ServiceA!
    service_b: ServiceB!
)