I see the start ratings for DNG files in Preview. The Preview Inspector pane doesn’t show much for HEICs.
Looking in the finder:
% exiftool -Xmp:Rating 2025-04-28-0001.heic
Rating : 1
% exiftool -Xmp:Rating 2025-04-30-0048.dng
Rating : 1
In both cases I’m not getting the files to show up with a star in Nitro.