As of my last update in January 2022, both "Honkai Star Rail" and "Genshin Impact" were popular games developed by miHoYo, but specific merchandise offerings might vary over time and region. You can typically find official merchandise for these games on various online platforms like the official miHoYo store, as well as other e-commerce websites such as Amazon, eBay, or specialized anime and gaming merchandise stores.

star rail official merch

Official merchandise may include items like figurines, clothing, accessories, posters, art books, and more. Additionally, you might find fan-made merchandise on platforms like Etsy or Redbubble, though the quality and authenticity of such items may vary.

For the most current and official merchandise offerings, it's best to check the official miHoYo store or their social media channels for announcements and updates regarding new products.