I'm going to put a dog poop bag on the sidewalk and pick it up on my way home
What will you do next to the dog poop bag?
Throw it into a trash can.
That is great to pick up after your dog. It's illegal not to.
I'm a dog owner so I know the rules since I'm responsible for picking it up.
You will always be a responsible person if you pick up your own dog's poop. There is nothing better than that, so accept my compliment. I think you're quite nice.