Especially now there are small museums in Tai O (tiny place, yet two museums!), there's surely scope for a museum on Cheung Chau.
Needn't be boring and stuffy. Like at Tai O, could have items and info from yesteryear - of course with plenty from fishing, but also local farming, plus temples, photos from the past etc.
Maybe even have staff in outfits from times past, help make it entertaining.