A general Shopify developer can usually handle Liquid sections, app setup, theme edits, and standard storefront changes. A Hydrogen developer is the better fit when the storefront needs React Router, Storefront API work, server-rendered product content, custom routing, SEO-safe migration planning, cart logic, analytics behavior, and launch QA in one system.
For growth-stage or Shopify Plus brands, the real hiring question is not whether someone can write React. It is whether the developer can protect revenue, SEO, product data, checkout handoff, and merchant maintainability after launch.