However, for the average fan in 2024 and beyond: The best way to experience the 100+ hours of content in Age of Calamity or the 200+ hours in Definitive Edition is to purchase them legally. The NSP files are out there, but the peace of mind of a clean, online-enabled save file is worth the price of admission.
If you're looking to manage or modify NSP files for personal use (e.g., for a homebrew or modding project), ensure you have legally obtained a copy of the game.
If you did not own the game, Nintendo’s official eShop price in 2021 was $59.99 USD (often on sale for $39.99). Age of Calamity was still full price, making the original a budget-friendly alternative.