Is "these ones" grammatically correct?

Not to make light of the question or the questioner, the first sentence has one mistake. It is that the word "these" is a plural noun. It is followed by a singular noun which is made to be plural by adding a letter "s." Your cannot makes a singular noun into a plural noun like the "ones" The corrected sentence is: "Would you like these."

The second sentence take the same grammatical error and mistakenly turns it in a singular noun into a plural noun by adding another letter "s." The corrected sentence is: "I was talking about these."

No, that is not grammatically correct. Would you like these? There is no need for the word "ones". It is understood which ones you are talking about. In the second sentence, remove the first "ones" and your statement will be grammatically correct.: These are the ones I was talking about.

I think it is grammatically correct.

I think William Shakesbeard wrote a play call "Yo, These Ones Over Here".

It's true you sometimes say "this one" or "that one," but you don't say "these ones." Maybe it's because "this" or "that" can refer to other things (like a situation) but "these" can't.