But Peter and they that were with him were heavy with sleep: and when they were awake, they saw his glory, and the two men that stood with him.
I guess the glory isn’t God.
1. The Apostles saw the Uncreated Light of His glory [Jn 1:14], but not by corporeal vision [Jn 1:18; 1 Tim 6:16]. With regard to the Transfiguration, St. Matthew uses the diction “there appeared to them” [Mt 17:3] and quotes our Lord as instructing the Apostles to “do not tell the vision to anyone” [Mt 17:9], and mentions that after the manifestation, the disciples saw only Jesus with their eyes [Mt 17:8]. Perhaps this hints that the vision of the Uncreated Light was not with the bodily eyes.
2. But aside from this speculation, the authority of three Great Doctors of the West suffices to show that the uncreated light is not seen with the bodily eye: St. Augustine [Epistle 147], St. Jerome [On Isaiah 6:1], and St. Ambrose [On Luke 1:2].