Perhaps try roasted fig coffee substitute? It's definitely not coffee but has enough of the same roasty flavor notes to be passable. With milk and sugar, I probably wouldn't notice it wasn't coffee if I wasn't paying attention.

Depends on your definition of healthy and sweet. ‘Healthy’ is vague and fairly subjective. Plenty of coffee substitutes exist, such as roasted chicory-barley mixes that taste decent and provide you with some fiber. Is it healthy?

I've had a roasted barley drink called "Orzo" in Italian McDonalds. It had some of those same roasted/caramelized flavour notes as in coffee.