Are nutrients absorbed in human esophagus?
For several reasons, I seriously doubt that this has been studied extensively.

There is a good reason to study absorption through oral mucosa because a drug or glucose can be held there by people who needing rapid absorption of a drug (e.g. sublingual nitroglycerine) or by people who may be unable to swallow (e.g. a hypoglycemic individual who has lost consciousness). Where there is a reason to know, there is a reason to study something.

The esophagus, on the other hand, is normally an area of rapid transport (a pill, or a fluid, for instance, is in the esophagus less than 10 seconds). While it's assumed that some pregastric absorption through the esophagus occurs and might be beneficial to avoid a "first pass" metabolism of the drug by the liver, there is no good method to keep a drug in the esophagus. With that in mind, absorption from the sublingual mucosa (where a pill might be held) is more valuable than what might get absorbed in as little as 6 seconds in transit to the stomach. From that point, it will spend significant amounts of time in the stomach, the various sections of the small intestine, and the large intestine.

Absorption of drugs from the rectum has been studied, because it can be used, once again, as a method of drug delivery when another route for whatever reason cannot,

Esophageal motility disorders occur, so studies of esophageal function are common. But as the esophagus is never normally the place for absorption of nutrients, there is no reason to study it except for the sake of satisfying pure curiosity. Studies take time, involve volunteers (or paid recipients), risk, and money. Pure curiosity is a reason to study something. But to get the all the previously mentioned factors to come together and fund a study, the reason usually outweighs pure curiosity.

Esophageal scintigraphy: reproducibility and normal ranges
Oesophageal transit of a radionuclide solid bolus in normals
DRUG ABSORPTION BY SUBLINGUAL AND RECTAL ROUTES