download Ryujinx, get keys by downloading them from a site (like from prodkeys.net) and you should get files "prod.keys" and "title.keys", place them in "./Ryujinx/system/". then you can go on a site like www.nxbrew.com, download nsp or xci files of the game (and a potential updates and whatever dlc), and throw them in folders of your choice (i personally have a "roms" folder with all my game files for different consoles, including a "switch" folder, with folders called "games" and subfolders "updates", "dlc", "mods", "cheats").

then, get on ryujinx, select the folder with your games as your game directory, and your games should be visible. you can right click on the game on the list and add updates or dlc, you can go to the mod directory ryujinx made for the game and add a bunch of folders with the mod data inside of it (for example, for ACNH i might have a folder called "360_camera" and inside of it will be a folder called "romfs"/"romFs" which will have a bunch of files/folders for the mod in it) and then select the mods to enable. for cheats you just need a folder named "cheats" in the mod directory and then you can put cheats for the game in plain text in the folder.

you can also mess with the graphics settings, use an input device (probably an xbox/playstation/switch controller), change datetime (although i find it doesn't allow you to make the date out of sync with your device's date, so you may want to go to your computer settings and manually change it if you want to do that), etc.

redditors even on piracy subs treat actually pirating things like it's voldemort, so when i wanted to emulate switch games it was a pain in the ass for me to find out what i needed to do, i hope this helps you not run into those issues lol.