Pomona's Pectin, if I remember correctly is a pectin/jelly-ing agent that. . .
works in a different manner so that it does not need a reaction with sugar to provide "jell" in jams and jellies.
I have never used it to make jams or jellies, but a friend of mine used to use it all the time because she did not want sugar in her jams, and she liked it.
As for regular jams being too sweet, I am with you on that. My kids won't touch a full-sugar apricot jam, but they love the jam I make with pectin that requires 1/3 less sugar, and so do I. I have used the light pectin on all sorts of fruit and it is excellent--EXCEPT for Santa Rosa Plum Jam (which includes the very tart plum skin); for this jam I use a full sugar pectin an like the results,
If you have not tried a "light" pectin that uses less sugar, I recommend it. I think the brand I use is Sure-Jell Light, which advertises 1/3 less sugar use on their boxes.