The message
from "Mike Lyle" contains these words:

An application of the principle which occurs to me is in
botanic or RHS etc gardens: a visitor could pick up the tool at the
entrance, and get, if he wanted it, far more information about a
plant than could be put on a label -- characteristics, history,
provenance, uses, mentions in literature, depictions in art, etc etc.
There are times when I'd like that at Kew and other places. In the
same way, it could be used with museum and art-gallery exhibits

It already exists, in all three applications you mention. Usually
available for hire at the entrance.

Janet