Does Wordle use proper nouns?
No, Wordle answers cannot be proper nouns. Similar to Scrabble, proper nouns like names of people, places, brands, etc. do not meet the criteria for Wordle's answer word list.
While a proper noun cannot be the answer, Wordle does allow some of them as guesses to eliminate letters. For example, you can enter a name like "JAMES" as a guess, and Wordle will indicate if any letters match. But "JAMES" or any other proper noun will never end up being the final answer.
Note that some words that are commonly used as proper nouns can still be the answer because they also have another non-proper-noun meaning. Examples include "Frank", which is a common first name but also an adjecive ("a long and frank discussion"), and "China" which is the name of a country but also a type of dishware.
"Frank" has already been the answer to a Wordle puzzle in the past, but "China" has not.