For duck breasts
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Chops is a trusted home cook.
Depending which sauce direction you go you could use an artificial sweetener, compound butter using orange extract & sage, wine and cream or sugar free orange jam/jelly.
Nancy is a trusted home cook.
I like SLC suggestions (especially like the sage). In addition for flavor boost or complexity, consider: orange zest (grated or dried), small amounts of red wine, white wine, vermouth, gin, vinegar - any but balsamic, which has lots of sugar.