I understand the question to be whether the meaning of διὸ indicates that Christ's exultation was earned or that it was given gratuitously.
On the meaning of διὸ in Phil 2:9 with this regard I refer you to this discussion of that subject on B-Greek.
As to "merit", "merit" is not in God's vocabulary:
[Rom 11:35-36 NLT] (35) And who has given him so much that he needs to pay it back? (36) For everything comes from him and exists by his power and is intended for his glory. All glory to him forever! Amen.
Paul specifically says that God is the source in contradistinction to Jesus:
[1Co 8:6 KJV] (6) But to us there is but one God, the Father, of whom are all things, and we in him; and one Lord Jesus Christ, by [IE: "through"] whom are all things, and we by [IE: "through"] him.
"Merit" is a corollary of the bogus concept of "supererogation". The folly of such "merit" with God is discussed sagely by Charles Finney.
However, YHVH is ever a faithful, covenant keeping deity who binds himself with oaths, covenants and promises and must fulfill all that he has committed to:
[Num 23:19 NLT] (19) God is not a man, so he does not lie. He is not human, so he does not change his mind. Has he ever spoken and failed to act? Has he ever promised and not carried it through?
So what we have in Philippians 2 is the last mile of Jesus' race, as described in Hebrews:
[Heb 12:2 NLT] (2) We do this by keeping our eyes on Jesus, the champion who initiates and perfects our faith. Because of the joy awaiting him, he endured the cross, disregarding its shame. Now he is seated in the place of honor beside God's throne.
Please see this question for what is meant by "the joy set before him".
So as I understand it, God set the race before Jesus and the prize was to sit at his right hand. Jesus ran the race, all the way to the bitter end and thus received the crown. But the whole thing was from God for his own purposes and was not imposed on him. Jesus didn't say, "I'm going to run around the perimeter of Jerusalem 40 times in a row and then God will owe something". That never works with God:
[Rom 9:15-16 NLT] (15) For God said to Moses, "I will show mercy to anyone I choose, and I will show compassion to anyone I choose." (16) So it is God who decides to show mercy. We can neither choose it nor work for it.
So Jesus did not "merit" anything with God except that in the sense that God set up a race of faith and since Jesus completed the race, he gets to sit with God and Jesus also, because that was the prize announced at the beginning of the race:
[2Ti 4:6-8 NLT] (6) As for me, my life has already been poured out as an offering to God. The time of my death is near. (7) I have fought the good fight, I have finished the race, and I have remained faithful. (8) And now the prize awaits me--the crown of righteousness, which the Lord, the righteous Judge, will give me on the day of his return. And the prize is not just for me but for all who eagerly look forward to his appearing.
[Rev 3:21 KJV] (21) To him that overcometh will I grant to sit with me in my throne, even as I also overcame, and am set down with my Father in his throne.
[1Co 9:24 NLT] (24) Don't you realize that in a race everyone runs, but only one person gets the prize? So run to win!
[Heb 12:1 NLT] (1) Therefore, since we are surrounded by such a huge crowd of witnesses to the life of faith, let us strip off every weight that slows us down, especially the sin that so easily trips us up. And let us run with endurance the race God has set before us.