Does the ending change depending on the percentage of completion?
Not in any significant way. Upon winning the game with less than 101% complete: just at the start of the endgame sequence, Cranky says a few lines about being sure there are some things you haven’t found yet. Upon winning the game with 101% complete: at the same point of the endgame, Cranky will instead congratulate you for finding everything. All of the rest of the endgame stays the same.
