The extant versions of the LXX Genesis 1:1 describes the making of the world using ἐποίησεν ("made") but the author of John, who seems to be commenting on Genesis 1:1 fails to follow the LXX verbiage and instead uses ἐγένετο. Might this be because the author is ascribing a particular role for the utterance in the overall making of biodome ("the skies and the land") and all therein?
ΕΝ ΑΡΧΗ ἐποίησεν ὁ θεὸς τὸν οὐρανὸν καὶ τὴν γῆν.
Swete, H. B. (1909). The Old Testament in Greek: According to the Septuagint (Ge 1). Cambridge, UK: Cambridge University Press.
Westcott and Hort / [NA27 variants] πάντα δι' αὐτοῦ ἐγένετο, καὶ χωρὶς αὐτοῦ ἐγένετο οὐδὲ ἕν. ὃ γέγονεν
I see that the LXX uses the word in and after the utterance of "Let there be (Γενηθήτω, the imperative form) light..." "and there was (ἐγένετο) light...".
Genesis 1:3 καὶ εἶπεν ὁ θεός Γενηθήτω φῶς· καὶ ἐγένετο φῶς.
Swete, H. B. (1909). The Old Testament in Greek: According to the Septuagint (Ge 1:2–3). Cambridge, UK: Cambridge University Press.
So clearly for John the logos was the utterance "let there be" in the creation of the light and the result was that the command resulted in the light coming into being.
I call attention to a passage that I think is related though it uses a different word for "word" (τὸ ῥῆμά μου):
NASB Isaiah 55: 10"For as the rain and the snow come down from heaven, And do not return there without watering the earth And making it bear and sprout, And furnishing seed to the sower and bread to the eater; 11So will My word be which goes forth from My mouth; It will not return to Me empty, Without accomplishing what I desire, And without succeeding in the matter for which I sent it.
10 ὡς γὰρ ἂν καταβῇ ὁ ὑετὸς ἢ χιὼν ἐκ τοῦ οὐρανοῦ, καὶ οὐ μὴ ἀποστραφῇ ἕως ἂν μεθύσῃ τὴν γῆν, καὶ ἐκτέκῃ καὶ ἐκβλαστήσῃ, καὶ δῷ σπέρμα τῷ σπείροντι καὶ ἄρτον εἰς βρῶσιν· 11 οὕτως ἔσται τὸ ῥῆμά μου ὃ ἐὰν ἐξέλθῃ ἐκ τοῦ στόματός μου, οὐ μὴ ἀποστραφῇ ἕως ἂν τελεσθῇ ὅσα ἠθέλησα, καὶ εὐοδώσω τὰς ὁδούς σου καὶ τὰ ἐντάλματά μου.
Swete, H. B. (1909). The Old Testament in Greek: According to the Septuagint (Is 55:10–11). Cambridge, UK: Cambridge University Press.
NASB Psalm 148: 4Praise Him, highest heavens, And the waters that are above the heavens! 5Let them praise the name of the LORD, For He commanded and they were created. 6He has also established them forever and ever; He has made a decree which will not pass away.
English Standard Version Psalm 33:6 By the word (logos) of the LORD the heavens were made, and by the breath (pneuma) of his mouth all their host. ... Psalm 33:9 For He spoke, and it was done; He commanded, and it stood fast.
So what are we to understand from this about who/what the logos is and his/its role in the making of Genesis 1?
Related question (on sister site): https://christianity.stackexchange.com/questions/60006/in-trinitarian-theology-who-created-the-world