Using a dynamic url with Feed Me
There's currently no method to parse variables into the feed itself through this, or any means. Typically, we approach this as feeds being third-party, or otherwise non-editable. How would you see utilising issueNumber to work in this scenario?

You can use the concept of aliases in your URL if that helps?

Lastly, you could also make use of the (undocumented) Datatype::EVENT_AFTER_FETCH_FEED event to perform any parsing on the feed once its been fetched?