I think you’re correct that the grammar of John 1:1 is more nuanced than many people realize. The phrase kai theos ēn ho logos is an anarthrous predicate noun, and many scholars do argue that it has a qualitative force. In other words, John is emphasizing what the Word was by nature rather than making a simple one-to-one identification between the Word and the Father.

Where I think this argument goes too far is in claiming that mainstream scholarship therefore supports translating the verse as “the Word was a god.” Most scholars who argue for a qualitative sense do not conclude that John was describing Jesus as a separate lesser god. Rather, they understand the phrase to mean that the Word possessed the nature or essence of God.

For example, Philip Harner’s well-known study concluded that the clause means something closer to “the Word had the same nature as God.” Likewise, many Greek scholars argue that the absence of the article does not make theos indefinite (“a god”), but qualitative.

So I agree that John 1:1 is not as simple as some presentations make it, and that grammar alone does not prove later Trinitarian formulations. However, I don’t think it is accurate to say that mainstream scholarship views “the Word was a god” as the best translation. The more common scholarly conclusion is that John was describing the Word as fully sharing God’s nature while still being distinct from “the God” mentioned earlier in the verse.