Yeah. I had come to that conclusion myself before reading his material on it, but now I'm not entirely sure. I thinking labeling it Apellean may be too ambitious.
I think the opening of John is original, i.e. it wasn't revised by some proto-orthodox editor. That being the case, it means that whoever wrote it had to view the Lord as the creator of the world. As far as I can see, Apelles didn't think that. Apelles thought that the world was mal-formed by an angel or lesser god.
But, I do think that whoever wrote the intro thought that Jesus descended directly from heaven, without being born. It would seem to me that if the intro were added or revised by some orthodox writer, then they would have clarified that Jesus was born of a woman. John does later say that Jesus had a mother, and his mother is part of the signs dialog, but it seems that various Gnostics had ways to acknowledging an "earth mother" for Jesus without accepting that he was actually born. I mean even Marcion did. After all, John 6:38 explicitly says: "For I have come down from heaven, not to do My own will, but the will of Him who sent Me."
Interestingly, the question about Jesus coming from heaven is brushed aside and not really answered, which also seems on-par with a Gnostic approach: "6:42 And they were saying, “Is this not Jesus, the son of Joseph, whose father and mother we know? How does He now say, ‘I have come down out of heaven’?” 43 Jesus answered and said to them, “Stop complaining among yourselves. 44 No one can come to Me unless the Father who sent Me draws him; and I will raise him up on the last day."
So the writer really left that thread hanging. I think an orthodox writer or reviser would have clarified this by saying that he didn't really come directly from heaven or something along those lines, to make clear that he was born of Mary. But that never happens.
So yeah, John seems to me to be almost entirely Gnostic, except maybe the ending. But is Apelles really the right individual to have written it? I think its better say that the work has many Apellean leanings. I also think it would be difficult for this to be a Gospel of Apelleas because wouldn't it have been recognized as such? I think it was most likely written in Rome, perhaps around 130-140, shortly after Marcion's Gospel gained traction.
And in Rome at that time there was a very broad spectrum of ideas that blended between Marcionism, Valentinianism and proto-orthodoxy. It would seem then that "John" was selected by the editor of the first edition of the NT because its strong monotheism and its pushback against Marcionite and Valentinian claims that Jesus was incorporeal and/or that the world was not made by the Highest God. But nevertheless, it certainly leans in the Apellean direction, just not all the way. Again, some people try to account for this by claiming proto-orthodox revisions, but I just don't buy the case that John was heavily revised. I thin it is what it is and it is mostly as it was originally written.