I’m going to try this recipe for making my own quinine syrup:
https://pinchandswirl.com/homemade-tonic-water-for-the-ultimate-gin-and-tonic/
But I’ll definitely be reducing the sweetness and using something other than sugar. Actually, I might leave it unsweetened entirely and mix on the go. Gives me the most flexibility.
I also like that it’s a syrup that gets mixed with carbonated water. That means easier to store, lasts longer and I have a soda stream because I love to make sparkling water already. Seems like a win-win for me.