A noun that describes the possession of esoteric knowledge
Esoterica
plural noun
things understood by or meant for a select few; recondite matters or items.
[Dictionary.com]
I would say “arcanum” (pluralized as “arcana”) most closely fits the definition you want. This is M-W’s first definition of it:
noun
: mysterious or specialized knowledge, language, or information accessible or possessed only by the initiate—usually used in plural
"Trivia" sounds like exactly the word you're looking for here.
From Oxford:
Details, considerations, or pieces of information of little importance or value.