Adding a featured topic to a Tag Banner

Hello, is it possible to modify this theme so that it also shows the banner once you enter a topic that has the tag? Would it be an easy addition?

I am trying to modify this theme to include a featured topic in the banner. I need to obtain the topic_id to generate the necessary url, but I only have access to the external_id of the topic (external_id is derived from a value in the description so I already have access to the external_id).

Is there way to obtain the topic url? I am quite new with discourse plugins and couldn’t figure how to fetch such an information via the javascript library.

The ideal output is as follows and it essentially let’s us pin a topic to a tag page.: