I'm using Sharepoint 2016's "term-driven pages with friendly urls" feature to return results for specific term-store terms, using a search result page that shows results for the specified term. I'd like to enable alerts on these pages. However, creating an alert using the default search alert button alerts for all changes to the site. I would like it to set up alerts only for results tagged with the term used. Is this possible, and how can I do it?
It is not possible to set alerts in custom scope if you plan to use the OOB search alert function.
SharePoint only provides three change types to set alert on and no other options are available. You will have to look for custom solutions like event receivers.
Another reference: SharePoint 2013 Search Alerts, Programmatically!