Paul is NOT splitting up different kinds of "works" into "works of grace", and "works of debt". He is saying that ALL works put the one you're working for in debt to you.
All those who walk by faith (2 Corinthians 5:7) and live by faith (Romans 1:17), God will give opportunities to perform works of faith. (Titus 3:8;Ephesians 2:10)
Right. And that also denies "salvation by faith AND works".
Romans 2:6-10
6 He will reward each one according to his works:
7 eternal life to those who by perseverance in good works seek glory and honor and immortality,
8 but wrath and anger to those who live in selfish ambition and do not obey the truth but follow unrighteousness.
9 There will be affliction and distress on everyone who does evil, on the Jew first and also the Greek,
10 but glory and honor and peace for everyone who does good, for the Jew first and also the Greek.
Romans 4:2-5
2 For if Abraham was declared righteous by works, he has something to boast about—but not before God.
3 For what does the scripture say? “Abraham believed God, and it was credited to him as righteousness.”
4 Now to the one who works, his pay is not credited due to grace but due to obligation.
5 But to the one who does not work, but believes in the one who declares the ungodly righteous, his faith is credited as righteousness.
Every time Paul refers to both "grace" and "works",
or "faith" and "works",or "mercy" and "works", he explicitly DENIES the "works" component.
Titus 3:8
8 This saying is trustworthy, and I want you to insist on such truths, so that those who have placed their faith in God may be intent on engaging in good works. These things are good and beneficial for all people.
Galatians 5:6
6 For in Christ Jesus neither circumcision nor uncircumcision means anything, but faith working through love.
Works do NOT mix at all with grace, they are mutually exclusive:
Romans 11:5 So too at the present time there is a remnant, chosen by grace.
6 But if it is by grace, it is no longer on the basis of works;otherwise grace would no longer be grace
Paul is only arguing here that if salvation were to come by works, apart from faith and grace then salvation would not be a grace or favor, but a debt.