For Unitarians? Since God is spirit per John 4:24 or a spiritual being and is invisible how is He able to appear physically by way of a Theophany?

The word theophany is a combination of two Greek words, meaning God and appearance. A theophany is an appearance of God. More precisely, it is a visible appearance of God. According to Jesus at John 5:37, "And the Father Himself, who sent Me, has testified of Me. You have neither heard His voice at any tinm, not seen His form." Also at John 6:46, "Not that any manb hath seen the Father, except he who is from God, he hath seen the Father." This raises the following question from Genesis 17:1-3, "Now when Abram was ninety-nine years old, the Lord appeared to Abram and said to him. I am God Almighty; Walk before Me, and be blameless, vs2, And I will establish My covenant between Me and you, And I will greatly multiply your exceedingly." Vs3, "And Abram fell on his face, and God talked with him, saying," I'm going to parapharse the rest. At vs4-6, God changed Abram's name to Abraham. God also stated He will multiply his descedanants and a King will come forth from his seed. Finally, God said this covenant will be an everlasting covenant to Abraham and his descendants. The reason this is a physical appearance of God to Abraham is from Genesis 17:22, "And when He/God finished talking with him, God went up from Abraham." So how do Unitarians explain "Biblically" the physical appearance of God to Abraham?