Product page graceful dependency degradation

Design graceful failover for a product-detail page service whose page depends on 6 downstream services (pricing, inventory, reviews, recommendations, images, personalization). The page is the top revenue driver and must keep rendering even when a downstream is slow or down, but pricing and inventory are correctness-critical while reviews/recommendations/personalization are nice-to-have. How do you isolate failures so one slow dependency can't take down the page, and what does 'degraded' look like?