There are fanfictions where the main characters react to different versions of their powers. For example, Gon and Killua reacting to a more powerful or darker version of their nen abilities. This can lead to interesting character development as they grapple with what they could become. It also allows the author to explore different power - up scenarios in a unique way.
Another way is to join Hunter x Hunter fan communities on social media platforms like Reddit or Facebook. Ask the members there for recommendations on good reaction fanfictions. They might be able to point you to some hidden gems that you wouldn't find through a simple search.
The Hunter x Hunter manga is unfortunately not complete. The author has faced various issues that have led to intermittent breaks and an unresolved storyline.
The Hunter x Hunter manga has indeed concluded. However, the ending might have left some fans wanting more or with mixed feelings depending on their expectations.