Hasura JWT_MODE with type ES256 using Cognito + ALBs

It seems like Hasura doesn't support JWT validation for tokens using the `ES256` algo, which is what the ALB (Amazon Load Balancer) tokens use.
> ALBs use an `ES256` JWT and public-key uri `https://public-keys.auth.elb.${region}.amazonaws.com/${kid}` for validation, whereas Hasura requires a `jwk_url`.

If that's the case, what are the workarounds? Or is it not possible?

My idea was to create a custom JWT validation Action handler, then funnel all GraphQL requests through it, but that seems hacky. Any ideas?

No source file, test, or entry point is named. Start by reviewing Hasura's JWT_MODE configuration and the ALB public-key URI behavior, then determine whether ES256 validation can be supported or what documented workaround applies; the issue is done when the support or limitation is clearly established.

Written by the indexing model from the issue text.