For oils, I’m sure replacing the walnut oil with grape seed, safflower or melted coconut would work just fine.
Date sugar or perhaps brown sugar could be used instead of coconut sugar
Any liquid sweetener could be used in place of coconut nectar. Honey, brown rice syrup or date syrup would probably work!
I don’t know whether or not substituting different flours would yield the same results but encourage you to give it a shot.
Perhaps you could make this recipe vegan by removing the eggs and adding in 6 tablespoons of water mixed with 2 tablespoons of freshly ground flax seed. Be sure to let the water and flax mixture sit for 5 minutes before adding into the recipe like you would an egg.
Recipe by Healthful Pursuit at https://www.healthfulpursuit.com/2012/08/strawberry-banana-muffins/