The game is roughly 9.5 GB to 10.5 GB . Ensure your microSD card has enough overhead for the update files, which can add another 2-3 GB.
For local wireless play, both Switch consoles should be on the same update version to avoid connection errors. ⚠️ Important Note on Safety It Takes Two Switch XCI Update DLCs
Hazelight Studios famously focuses on complete experiences. There are currently no paid expansions or "Level Packs" available. The game is roughly 9