"Nous" means "we" and is the proper choice.
"On" means "one" (derives from Latin "homo" for "human"), but it's also used in informal speech in place of "nous".
English use of "one" as a 'passive agent' derives from French "on" (as in "... but whether one ought to comply is a different matter.").
Here, in Australia, using "one" is considered as something only the British upper classes say and would be embarrassing. We use either "someone" or change to the plural "we". For example, "one doesn't do that" becomes "We don't do that". Australians like to be direct about what one does or doesn't do in polite company. (Now there is subtle nuance for you!)
We don't really make that distinction in the States. We're much more likely to replace "one" with "you" or "we" in informal speech, and using "one" does have somewhat of an educated tone to it, but it doesn't sound particularly elitist, and in writing it is what... one would use.
The long thin slicing of potatoes for frying only appeared in Australia during the 1960s with the first American fast food restaurants. Traditionally we have had the short cut pototoes fried as 'chips' as in the British 'fish and chips'. Except in the chains, chips are the norm. The American cut is called 'julienne' in cooking, 'string' when bought frozen from supermarkets or 'straw' when used in a packet of crisps. A good discussion of the etymology of French fries is at http://www.worldwidewords.org/qa/qa-fre2.htm. 'Wish' would be used only if the chances if getting them were unlikely such as being marooned on an uninhabited island.
I'm Australian and agree that we don't say "we wish for fries".
We might say "we wish we had (hot) chips", to express regret at not having them at that moment, but if we're expressing a desire to have them, we'd probably say "we'd like (some) chips", or "we want (some) chips".
(This comment for those wondering what Aussies do say, and I realise this may not be many of you! Also, sometimes we say "some", but it's just as common to leave it out.)
Australians aren't renowned for being oblique in their conversational styles.
I wrote, "We are wishing for French fries," but Duo rejected it, supplying an answer of We are hoping for French fries. I know a subtle distinction can exist between the three forms of the present indicative in French, but I thought surely "are wishing" was as idiomatic as "wish" here.
This sentence sounded like a Duoism so I tried "We would like some chips" and behold, it was accepted. Do French people really "souhaiter" a bag of chips? The structure seems very elevated. "Oh!" said the Queen. "One could wish for a bag of chips, just like what they do down the East End". Sighs wistfully.