I Will Follow You Into the Dark

If heaven and hell decide that they both are satisfied /
Illuminate the NOs on their Vacancy signs //
If there’s no one beside you when your soul embarks /
Then I’ll follow you into the dark //
- with much gratitude to Ben Gibbard

Rules:
Normal Sudoku rules apply.
There is one single gray palindrome line, on which digits an equal number of cells from the center of a line are the same.
In cages marked with a dashed line, digits sum to the small number in the top left corner of that cage.
Cells separated by a white dot contain consecutive digits. In cells separated by a black dot, one digit is double the other. Not all possible dots are given.
Correct digits reveal the cells surrounding them, up to eight.

Estimated difficulty: 1 out of 5