Even if you buy the game you need to bypass encryption in order to dump the game data to run it on an emulator. A big part of why Nintendo prevailed in their lawsuit against Yuzu is that they proved the emulator could not be used without extracting encryption keys and bypassing copy protection.

So no, there's no legal way to use a switch emulator. At least not for playing commercial switch games, I guess you could theoretically home brew your own game to play on an emulator.