I suppose you might be able to capture a frame, invert it (e.g. using an image processing library) and then try detecting the data matrix in the inverted image using Expo’s BarCodeScanner. I’m not sure how well this will work.
Alternatively, it seems that these commercial barcode scanner libraries all support data matrix barcodes and they all seem to support scanning inverted barcodes too. I have not tried any of them: