Pectin vs Agar Agar vs Gelatin for Pate de Fruits
There are plenty of high-sugar-content sweets that use gelatine, so it would be a reasonable substitute, but won't match the texture that pectin would normally provide in a pate de fruit or jam.

I don't know of any recipes using agar-agar that are designed for long-term storage, it is more often used in desserts, and again has a very distinctive (slightly crunchy to me) texture