How to return a stream from AWS ApiGateway? – Amazon Web Sevices

Can someone tell me how to return a stream from an AWS Api Gateway?
My API calls a lambda written in C#, which successfully returns a string, but I don’t know how to modify it to return a stream.
I need this because it will be used to download a zipped file that is 100MB.

This is a simplified version of my current lambda handler.

    public APIGatewayHttpApiV2ProxyResponse MainHandler(APIGatewayProxyRequest request, ILambdaContext context)
    {
        ...
        var response = new APIGatewayHttpApiV2ProxyResponse
        {
            StatusCode = (int)HttpStatusCode.OK,
            Body = "MainHandler was called",
            Headers = new Dictionary<string, string> { { "Content-Type", "text/plain" } }
        };

        return response;
    }

I don’t know how to modify this to return a stream, instead of text.

I have found examples of how to consume a stream using HttpClient:

c#: How to Post async request and get stream with httpclient?

but no examples of how to create one from AWS.