The song is "Close in the Distance" and plays in the final zone, Ultima Thule, after completing the quest "Hello, World". These are the lyrics I've found so far.
Whispers falling silently drift on the wind,
But I hear you.
Our journey, now a memory fading from sight,
But I see you.
Unbroken promises we made so long ago,
You're still here.
Unspoken requiem for a river of tears
Flowing, winding, to one eternal sea.
And yet, our hope remains,
Guiding, lighting the way.
No time for mourning
Rises on a mem'ry borne from the ashes
With the heavens
To sunset, blood-red skies tranquil after the storm,
Blessed shadow.
Turning, wending, always night follows day.
The sun will shine again.
Walk on, never look back.
Through you, we live.
Tales of loss and fire and faith(?).
Every word out hearts and impaled.
In the dark, you will not stray.
Forge ahead, till the end, we pray.
I'm 90% sure I have everything right except the first two lines of the final stanza. I think the final word of the first line is "faith" but it doesn't rhyme with the final word of the second line which clearly ends in an "L" sound.