Rehydrate the blueberries and make a sweet-sour or sweet-sharp sauce with some lemon juice, sugar, and fruit juice on hand (orange, cranberry etc.)...or boost a sugar syrup with some pomegranate molasses or cranberry sauce and the re-hydrated blueberries.
As Amanda Sims said, alone they won't make a sauce; but they will be good with other things.
For a more promising swap, I'd rehydrate them in some warm water first. Here's a thread with more answers about using dried blueberries in place of fresh or frozen ones: https://food52.com/hotline/2925-can-i-use-dried-blueberries-in-place-of-fresh-frozen-in-recipes-such-as-blueberry-boy-bait-muffins
What kind of sauce are you thinking of making? They won't cook down to a saucy state the way fresh fruit will (but they'd probably be excellent dropped right in the bready part of the bread pudding).
4 Comments
As Amanda Sims said, alone they won't make a sauce; but they will be good with other things.