How do you share an Input object across federated schema

[purpleD17]

I'm looking for a way to shared federated schema for InputType. Fore example shareable or extends. The goal is to have one graph advertise shared InputTypes that many subgraphs can build mutations around. Right now I don't think this is possible based on the documentation. If not, can it be a featured added to federation?

Graph1 has no queries or mutations just shared InputTypes:

input UserInput @shareable{
  firstName: String!
  LastName: String!
}

Graph2 has a mutation:

type Mutation {
   doSomethingWithUser(userInput: UserInput!): String!
 }

Graph2 also has a mutation:

type Mutation {
   doSomethingDifferentWithUser(userInput: UserInput!): String!
 }

Is this possible?