> I think people's sensory experiences vary wildly by nature, but we have no access to them so can't really prove anything.
> ... some people have photographic memories (e.g. Lebron James apparently); some people can factor large numbers in their heads (computation), or recite huge strings of digits (non-episodic memory).
Many of these sensory experiences can be empirically and objectively analyzed. For example, photographic memory is not a real thing. Nobody has ever shown the ability to recall particular details of a scene which they hadn't already focused or been cued on. There's been considerable, sincere effort invested in testing these claims, both in claimants and random individuals. (There are people who remember endless amounts of seemingly non-episodic daily trivia of their everyday life for literally every day of their life, but this isn't photographic memory and definitely doesn't describe LeBron James.)
Large number mental arithmetic and recitation of long strings (or other trivia) is a learnable skill, though many people develop the skill independently, many of whom describe their techniques in a manner that comports with well-known techniques.
Sources: "Moonwalking with Einstein: The Art and Science of Remembering Everything" by an American journalist who became the American Memory Champion as part of his research; "Your memory: how it works and how to improve it" by Kenneth L. Higbee, a professor of psychology who has a personal interest in mnemonics techniques; and "The Art of Memory" by Frances A. Yates who traces the historical practice of the Method of Loci from Ancient Greece and its transformation into esotericism by the time of the Renaissance.
Of course, there's no accounting for people who believe and feel they have a photographic memory[1], just like there can be no accounting for people who believe they're being personally surveilled 24/7 by hidden cameras everywhere. But that doesn't mean I have to accept that there are some people who are actually inexplicably and secretly being surveilled; left to wonder why I'm so lucky/unlucky.
Conversely, there are some people with a real, extraordinary sense, like tetrachromats (https://en.wikipedia.org/wiki/Tetrachromacy#Humans), who have a fourth peak in their color spectrum reception. They see the world in much richer color than normal humans, and this has been empirically verified.
[1] Indeed, I'm pretty sure most people (myself included) feel like they can shut their eyes and retain a photographic picture of a scene. I was told I had a photographic memory by many different teachers, going back to at least third grade. But, again, it doesn't stand up to scientific experimentation. And I never believed my teachers as it was always self-evident to me that while I may have remembered more seemingly esoteric facts or events than they did, it was because I had consciously found those things curious, however briefly. (As an adult I was diagnosed with ADHD, which perhaps goes a long way to explaining why so many things caught my attention.)