Natural antifreezing agent for Ice Creams

Glycerin or glycerol is an effective antifreeze; It's food safe, environmentally friendly and natural..

Thanks for the suggestion. But glycerol/glycerin is still an additive. I'm looking for a natural alternative which is not commercially produced or manufactured in the lab

..🤔 BTW... It does not make sense.. You make an ice cream so you had freeze it up to harden... If your ice cream formulation is balanced and freezer temperature is right then you will get the typical texture of average cream with finely distributed crystalline particles that is flexible to scoop.. IF it becomes rock hard then your recipe is not balanced due to the reason you are not using functional additives like emulsifiers, gums and other stabilizer.. YOU ARE LIKELY MAKING AN ICE CANDY, which is just syrupy mi,xture of sugar, water, your functional ingredient.. 😁
How about giving us more details what are you really trying to achieve.. Show you'd recipe, how did you process it and what is your specific objective..?

Sugar and fat are going to mitigate hardening of your frozen dessert (it's not ice cream).
Dry modifying the amounts of these. If you are going for low fat and/or low sugar you are out of luck, unless you want to add alcohol, which is a pretty expensive option.

It's difficult to find a raw ingredient or non additive that will perform that role. What you're looking for from your description is an emulsifier and stabilizer that will prevent large ice crystals from forming due to water migration. You can try sprouted soy flour because it has been used to replace eggs in some foods. You can do the rest by testing yourself. You have to determine the pre treatment, the amount that will not affect the taste e.t.c.

https://www.fiberstar.net/2020/06/02/natural-ice-cream-using-citrus-fiber-blog/

Citrus fibre, it can be labeled as citrus flour. I have used it for some other product.