Yes. As described at https://www.food.gov.uk/terms-and-conditions , the hygiene ratings information can be re-used under the OGL. The required attribution is included at https://wiki.openstreetmap.org/wiki/Contributors#United_Kingdom . There's also an OSM Comparison tool at https://gregrs.dev.openstreetmap.org/fhodot/ that can be used to help match objects and spot missing entries.