create Photo Gallery from plugin code

Hello

I’m developing a custom theme for a client. We are using a custom post type to retrieve some data from another website. So I made a plugin to create the custom post type, and add the the data as new posts of this type. Now I need to add a Photo Gallery, with the images I retrieve, to the content of this posts, and I need to do this from the plugin code. It’s possible to do this with your plugin? Can I create a Photo Gallery from source?