How to do Rate Limiting at the Gateway without Cost Directives

From my reading of: The gateway - Apollo Federation - Apollo GraphQL Docs it appears that type-level directives are stripped before the gateway pulls schema from the uplink. Is it possible for the gateway to retrieve that information in some other way so that it can apply some static query analysis before permitting requests?

I’m hoping to implement the cost directive spec (GraphQL Cost Directives) from IBM that Github/Yelp also appear to use.

If there are other ways to re-create a similar system without type-level directives, I’d also be interested in hearing about those!

Thanks so much