The problem with:
“No one has ever seen God [accusative]; the only (one) God [nominative]. The one (being) [nominative] in the bosom of the Father (OR sitting at his Fathers side) he has made Him known.”
the accusative is the direct object of the sentence and the nominative cannot be in apposition with the accusative, but is the subject of the next sentence, in other words is in apposition with "the one." Thus, that punctuation is misleading in English as far as the meaning of the Greek grammar. The next translation is OK:
“No one has ever seen God. The only son; the one (being) in the bosom of the Father (OR sitting at his Fathers side), he has made Him known.”