How to make shelf-stable gummie candy in a home kitchen?

I made this recipe for sour gummies:

Gummies

• 2 C / 473ml fruit juice (I used apple)
• 2.5 C / 600ml water, divided
• 4.5 tsp citric acid
• 6.6 oz / 187g gelatin
• 22.4 oz / 625g sugar

Coating

• 6 T sugar
• 3.5 tsp citric acid

The instructions say that they will keep on the counter for four days or in the fridge for three weeks. That’s fine, but I would love to make shelf-stable candies if possible. How, if at all, can I do that without industrial chemicals and equipment?