A non-geographically connotated phrase to express "too localized"

Background (may be skipped):
Over on Crypto.SE we're currently reforming our custom close reasons and as a result of this, we want to create a close reason that captures both "request to analyze a chunk of data which will help nobody else" and "request to fully peer-review a self-invented scheme which will never be used, never be useful to anybody else, is too broad and beyond our capabilities", i.e. something like "too localized" while avoiding this specific wording because it was retired by SE itself and comes with too much connotation for "geographical", "timely" and "language-bound".

This results in the following needs:
I'm looking for a word or a phrase to (elegantly) express "too localized", i.e. that something is very specific to one person and will likely never be used / needed by somebody else.
I thought about "too localized" but I'm sure it will be misunderstood in a geographic, language-bound or timely manner, like "this is 20 years old (or only exists in north korea), nobody cares about it, it's too localized" is the kind of thing I want to avoid.

How about too narrowly focused?

Or Not generally applicable.

Esoteric Merriam-Webster

: only taught to or understood by members of a special group : hard to understand : limited to a small number of people

This is often used to describer a very niche interest, such as certain programming languages, or someone who has a deep and abiding interest in Swiss postage stamps from 1833-1838.

List of Esoteric Programming Languages