So, the emulator did not contain the key but it made it easy to use one if you had one? Is that a suitable description? How useful would the emulator without t

So, the emulator did not contain the key but it made it easy to use one if you had one? Is that a suitable description? How useful would the emulator without the key be? I guess you could still write and play (and share) your own software. Is that what people call "homebrew" in the Nintendo Switch context?