Nominalizing adjectives regarding nationalities

When we talk about nationalities, "Americans" and "the Americans(or the American people)" are two ways of saying the same thing with the latter having a collective sense. The same is true for "Italians" vs. "the Italians(or the Italian people)", "French people" vs. "the French(or the French people)", "Japanese people" vs. "the Japanese(or the Japanese people), etc. Is it perfectly fine to say "the American (as a plural)" to mean the same as "the Americans or the American people"; "the Italian (as a plural)" instead of "the Italians or the Italian people" to refer to them as the nation as a whole?

Some national adjectives are taken as plural nouns when used alone: e.g. "the British", "the English", "the Welsh", "the Scottish", "the Irish", "the French", "the Japanese", "the Chinese", are easily used to refer to the people as a whole. (This may possibly have to do with the words' endings.)

Some national adjectives are singular nouns when used alone: "the American", "the Canadian", "the Mexican", "the Egyptian", "the Italian", "the Australian", all mean individuals, unless used in a metaphorical or generic sense ('the typical American....', 'the Ugly American').

"The Turk" is an individual; "the Turkish" are his people.