Sealing a stained cutting board
Yes. The extent to which that is &quot;sealed&quot; is debatable, but there's certainly no issue with finishing over cured stain - it's done all the time.
Just stay food safe (and be sure to check with your guests about nut allergies if using something like walnut oil, which is a good food-safe hardening oil, but not great if you have a guest with tree-nut allergies at a very sensitive level...)