For a few years I was a laboratory technician in a jam factory
Strictly speaking, you cannot have low sugar jam as by law anything called jam must have a minimum sugar content in order to preserve it. That's why you can leave an opened jar of jam in a cupboard for weeks & months
IIRC the level was 61,5% TDS = Total Dissolved Solids, though it was years ago and I could be mistaken over the exact figure, but it was somewhere around that
The way to achieve that is to mix fruit, sugar, and pectin then boil it, which evaporates off some of the water, and breaks everything down to create the sticky/glutinous/jelly- like structure we call jam
Commercial and home made jams use the same sort of method.
Top quality jam is mostly fruit & sugar, with cheaper jams having more pectin
You can get so called low sugar jam. These are various spreads and compotes containing less sugar but more pectin and artificial sweeteners to obtain the required structure & consistency and sweetness
Search Google and YouTube for 'low sugar jam'
There are several types available to buy, and recipes
As these contain less sugar they must be kept in a fridge, and have a shorter shelf life
Here's a suggestion - make your own or buy best quality jam or homemade jam from summer fetes and so on
They will usually have a higher fruit content resulting in a stronger flavour, so you will need less of it
I remember years ago, before I had D seeing a recipe for apricot spread made by simmering together soaked chopped dried apricots, spices, and a very small amount of brown sugar to make a 'jam' that had the minimum of sugar
It did mention that it had to be kept in the fridge