Q:

GraphQL specify array of multiple types

Is there any way to tell GraphQL that a type is an array filled with Strings OR Integers?  Basically this, if it were valid
inputHelper: [[String | Int]]

So in a query I could validly send over
inputHelper: [["foo", 1], ["bar", -1]]

A:

You could potentially create a custom scalar that could accept either integers or strings.
The easier solution would be to utilize an existing JSON scalar, like the one here. Then you could just do:
inputHelper: [JSON]

or just
inputHelper: JSON

