In Deuteronomy 10:10, Moses says, “The Lord gave me the two tablets on which God has written in his own finger all the words he had spoken to you from the heart of the fire when you were assembled at the mountain.” Moses appears to be saying that God literally wrote on the stone tablets. Since that seems to imply a hand to either hold the writing tool, or at least a finger to engrave them into the rock, and Jesus is God in the flesh, could this have been Jesus whom Moses was talking with on the mountaintop?
He did see the Lord face-to-face (Exodus 33:11). This would mark another time pre-New Testament that Jesus possibly walked the earth. The other time being the possible true identity of the high priest Melchizedek (Genesis 14:17-20). And another being in Eden walking “about in the garden” (Genesis 3:8).
People were not able to behold God in His full form because they’d probably melt like in Raiders of the Lost Ark or something. However, Jesus is God and thousands upon thousands of people saw His face and witnessed his teachings almost 2000 years ago. God, as Jesus, can be seen and approached.
This leads me to think that when people in the Old Testament walked or talked with God besides it being a burning bush, cloud of smoke or pillar of fire, it was Jesus they were beholding.
Some researchers say that when “Angel of the Lord” is referred to in the Bible, it is speaking of Jesus. Ruler of the angels and everything else.