If you just want a histogram of all the chemicals that are present, that would probably be doable if not already done. But how would you even quantify/qualify the "sensations" of those senses?

Vision is "easy": What I see is what you see is what the machine sees.

A machine shows us what it sees and we can verify that it is working correctly, with a glance.

How would we verify that a machine smells or tastes "correctly"?

> a histogram of all the chemicals that are present, that would probably be doable if not already done.

I'm no olfactory biochemist, but that sounds like science-fiction to me. The, er, reference implementation we're talking about is advanced nanotechnology we don't fully understand.

While we can do stuff like mass-spectrography, that involves destroying complex chemicals and converting them to smaller fragments we can tally, and then guessing at possible configurations they might have originally had.

If someone had a device that could simply tell you the exact chemical formulas of all molecules of any kind in a sample, it would be used everywhere and they would be very rich.

The machine smells correctly, when the same numbers (or similar when using some norm, e.g. the L2) appear for the same smell (reproducibility) and therefore a mapping (numbers -> smell) can be created. When this starts to exist (practically usable), there can be a database to store the mappings, allowing classification. E.g., the machine says "this tastes like banana". The machines/algorithms/products could itself be rated for precision.

I dont say such machines don't exist, but for my taste (pun intended) the solutions all lack something, either long term stability or having a second source supplier or being able to classify a reasonable amount of tastes or being able to distinguish between two tastes (or lacking all those things together).

The machine would need to reproduce the smell just like it reproduces what it sees on a screen. What the sensor "sees" isn't what our eye sees either.