In Acts 2:36 God’s exaltation of Jesus culminates in his being declared “both Lord and Christ”; the title κύριος carries precisely the Septuagintal resonance that the objection says Luke never entertains.
Again another subtle but important misquotation. Acts 2:36 doesn’t say Jesus was “declared” Lord and Christ at his exaltation. It says that God “has made” Jesus Lord and Christ. Firstly, nobody ever “made” God Lord, he is Lord by right. If Jesus was “made” Lord, as Acts says, then he is clearly not God, of whom this could never be said. Secondly, the author of Acts makes it extremely clear that Jesus, as Lord, is distinct from YHWH in his quotation of Psalm 110:1 where Jesus as messianic Lord (adonai) is distinct and subordinate to YHWH.