I think you are confused by that section of the manual.
If a remote site queries a PHP script on your site, all it gets back is data. Not PHP code. The PHP is parsed and processed by YOUR Web server, not the remote (client) site. That's what the manual says.
If you want to supply data to another site, simply write a script that serves up the data in a format the remote site can understand.
The data might be served up as HTML, or plain text, or binary images, any other format that can be generated by PHP.