this plugin shows you how to create new routes, and static templates. I should update this example to show how to utilize dynamic templates but it would be something along the lines of
(totally off the top of my head... but yeah when I get the time I'll update the plugin to do the above)
It's called nodebb-plugin-iframely, not updated to v1.x.x yet thought. Created issue https://github.com/NodeBB/nodebb-plugin-iframely/issues/16 for this.
ghost created this issue in NodeBB/nodebb-plugin-iframely