There is no single “secret” tool — serious sellers triangulate across several free and paid sources:

Free

• Google Trends — confirms whether interest in a product/category is rising, flat, or declining over time; also lets you compare regions.
• Meta Ads Library and TikTok Creative Center — both let you see ads currently running publicly. If a product has been running as an ad for weeks, that’s a strong signal it’s profitable for someone (ads that lose money get pulled quickly).
• AliExpress “Dropshipping Center” — shows recent order-volume trends per product, directly from the supply side.

Paid (worth it once you’re past pure validation)

• Sell The Trend / Ecomhunt / Minea — aggregate trending-product data and winning ad creatives across niches.
• Jungle Scout / Helium 10 — Amazon-specific keyword and sales-estimate research if you’re selling there.

On “datasets”

There isn’t a single downloadable master dataset of “winning products” — anyone selling you one is selling stale, already-saturated information. The tools above are effectively live, constantly-refreshed datasets, which is exactly why triangulating 2–3 of them is more reliable than trusting any single source.