Custom link data-attributes

Given that this feature explicitly does not want user interaction -- i.e., specific types of links should receive these data attributes consistently -- would an alternate, potentially simpler solution, be to create a text format filter for links in rich text fields, and/or to create a link formatter that extends Drupal core's formatter for link fields?

I thought I could get away with this by creating a link template for my custom entity and specifying that in the matcher. While that was working, I wanted the link element to also have additional attributes added automatically (because this specific entity match should open in a modal window) - i.e. let JS take over. Without requiring any additional action from the editor. I could not figure out how to modify the element before it was added into CKEditor to have that.

I guess my only option because I am crunched for time is to add in https://www.drupal.org/project/editor_advanced_link → and add a custom checkbox or two and work the rest from JS.