"Japanese doesn't use articles"...so then what's up with 一つの and 一匹の?

I'm reading a beginner story on the yomu yomu app, and the aforementioned words are being translated as "a" or "an" in the app. Examples from the story:

一つのリンゴ = "An apple"

一匹の猫 = "A cat"

I know these are ways of counting 1 of something, so it makes sense to me why the translator would choose to use a/an for English learners, but my question is:

Do native speakers use these words to convey the same kind of "a/an" meaning when speaking, or is this kind of usage reserved for writing/stories only?