This extension does not push images automatically, because of huge traffic overload when using responsive images. Each image in the picture source would be pushed to the client.
composer require codemonkey1988/script-style-push
You can add custom resources to push. Just add a comma separated list of asset paths to the site configuration. Just add a comma separated list of assets. Keep in mind, that this might change in the future as TYPO3 supports additional custom field types for site configuration.
This extension help you preventing over-pushing of assets by setting a session cookie that contains all assets that were pushing during the user session. This extension will not push an asset, if it's in the cookie. This feature can be disabled in extension settings.
If you need to disable generating the Link header,
you can do this by setting the env variable
SCRIPT_STYLE_PUSH_DISABLED to 1.