Imaginary's built in server and offical docker image does not provide long lived cache-control headers, but you can add them but utilizing a reverse proxy in production.

imgproxy's built in server and offical docker image does not provide long lived cache-control headers, but you can add them but utilizing a reverse proxy in production.

ShortPixel Image Optimizer (the plugin being tested) serves images from your own WordPress server, it is up to you to serve it via HTTP2+. Therefore, this is not applicable. ShortPixel does have an API, that does include long lived caching headers in it's response.