@plantaseed Great question Romans 4:4-5 is simply saying that unlike the money we get paid for doing our jobs, the salvation God offers is not something that we have earned by our effort - it is a free gift of God’s grace. None of us can boast in what Christ has done in our lives because it is completely undeserved and unearned.
Regarding Romans 4:17, it appears the best understanding is that God is able to call nations into existence even though they do not yet exist. God promised to make of Abraham a great nation and God was able to declare that truth even before it had happened. God could bring His promises to pass.
I think this quotation from Isaiah 46 summarizes God’s ability to bring to pass what is not yet well (in contrast to idols):
“Remember this, keep it in mind,
take it to heart, you rebels.
Remember the former things, those of long ago;
I am God, and there is no other;
I am God, and there is none like me.
I make known the end from the beginning,
from ancient times, what is still to come.
I say, ‘My purpose will stand,
and I will do all that I please.’
From the east I summon a bird of prey;
from a far-off land, a man to fulfill my purpose.
What I have said, that I will bring about;
what I have planned, that I will do.
Listen to me, you stubborn-hearted,
you who are now far from my righteousness.
I am bringing my righteousness near,
it is not far away;
and my salvation will not be delayed.
I will grant salvation to Zion,
my splendor to Israel.