You can add hours to OSM.
I know. So? Usually the businesses maintain their own opening hours (and if they are on top of things their business holidays) on Google Maps. The current state is that for looking up opening hours GMaps is leagues ahead of anything else and for actual navigation the competition (or in case of Waze the adopted sibling) is better than GMaps.
If any other messenger had the same issue, Moxie Marlinspike and fans would have an outcry on biblical proportions.