API Gateway straight through connection

Question

We have multiple APIs with many endpoints in each one and these APIs are protected using oAuth so a token is required to access any of the APIs.

We will eventually break these large APIs into microservices but for now I need to try and add a Cloud Run instance to a GCP API Gateway that will basically just proxy any request through the gateway to the API backend allowing the API to function "normally" including passing through the token so that the API can process that itself.

I have heard a "straight through connection" mentioned before but I've not been able to find any real information about this so it may not actually be possible.

I also get that this kind of goes against what the OpenAPI spec is supposed to be used for but ideally something like the following is what we currently want:

paths:
 /myapi/*:
    get:
      security:
      - Bearer: []
      summary: Pass calls to my-api
      operationId: get
      x-google-backend:
        address: https://my-api-12345.run.app/    
      responses:
        '200':
          description: OK

so that I could call https://gw-adsgae.gateway.dev/myapi/info or https://gw-adsgae.gateway.dev/myapi/customer and that it would go through the gateway passing the bearer token to the API in the Cloud Run instance without having to actually specify all of the individual endpoints and separate paths in the OpenAPI spec for the Gateway to match all of the endpoints in the APIs behind the Gateway

Is this generic/wildcard path spec possible at all?

Is there a way to pass the token through the Gateway without the Gateway trying to do anything with the token?