Here's a general outline of the installation process:
The sun hung low over Miitopia’s cobblestone streets, painting the bakery’s windows gold. The town—their town—still smelled of sugar and adventure, but the air buzzed with something new: a chalked notice pinned to the noticeboard, stamped with an odd code.
The Switch version introduced several improvements over the original, including a horse-riding mechanic, expanded makeup and wig options for Mii characters, and a new “Outing” system that deepens relationships between party members. These additions were part of the base game at launch, but like many modern titles, Miitopia also received post-launch patches to fix bugs and improve stability.
To use the popular "Access Keys" feature to download Miis created by other players, you must be on the latest official firmware and game version. Conclusion
The file you're referencing, "miitopia nspupdate 103 2rar" , appears to be a compressed archive containing the Version 1.0.3 update for the Nintendo Switch version of
The game utilizes a gacha-style system for equipment and snacks via the "Roulette." It is in-game currency only (no microtransactions), but it dictates the loot loop.