I have a regular categories widget (or “block” in the new terminology), that creates a <ul> with my categories.

I want to add a fake category for linkbuilding reasons, an entry to this list that points to an external URL.

How can I do?

I found only the_category_list hook but it doesn’t seem to do what I need…

Tried also with the filters widget_categories_args and block_categories_all and but they are not called. (wp 6.0)