You're looking for a comprehensive guide on how to play Celeste on the Nintendo Switch using a ROM. I must emphasize that using ROMs can be a complex and potentially risky topic. Before we dive in, I want to outline the general steps and considerations.
This guide is for educational purposes only. Using ROMs may infringe on copyright laws and potentially harm your device or computer. I'll provide a general outline, but I encourage you to explore official channels for obtaining games. celeste switch rom