This was very cumbersome to maintain not just as an editor, but also as a developer. So I decided to take a look at my Plausible analytics and find out if anyone had ever even visited a category page. Turns out… not a single visit! Tags? Yes. Categories? No.
A decision was made to remove categories entirely from my site. Now I just use tags, and use 11ty’s in built methods for tags as opposed to maintaining my own. After all, that is the whole point of using an SSG built and maintained by someone else.