Soda pop has about 400g of sugar per gallon, a little under a pound. I’d add one ounce of the flavoring and a pound of sugar to a gallon jug and fill with water to get a final volume of 1gal. I’d then add yeast and later in the day bottle in plastic 2L or smaller bottles. Plan to drink this within a week and keep in the fridge once you get enough carbonation. The plastic bottles will get firm when carbonation is adequate. It shouldn’t have more than a couple tenths of alcohol when carbonated, but it will continue to go up unless you keep it good and cold.
I used to make this stuff for family gatherings and my nephews loved it. Later on they told me they liked it because it gave them a slight buzz.
