In your case, I’d recommend using ‘available: no’ but keeping the page indexed. Let the product page breathe on its own, especially if it’s generating traffic. The redirect method is great for discontinued items, but for seasonal or older SKUs, keeping it live with related product suggestions is best.
I read this marketing strategy guide recently that showed this tactic works especially well in medical niches, where old service pages still bring in leads even after the service changes. Same logic applies here