Somebody has fed you or you have invented bad information. Neither Yuzu nor Ryujinx, the two Switch emulators which recently ceased development due to intervention from Nintendo, included Nintendo's code. The Yuzu settlement required those developers to acknowledge that

because our projects can circumvent Nintendo’s technological protection measures and allow users to play games outside of authorized hardware, they have led to extensive piracy.

There was never any mention of them stealing Nintendo code.

Ryujinx, we know even less about, because the agreement went down privately, but there's literally zero indication of any stolen code. We know that Nintendo contacted the developer proposing that they cease offering Ryujinx and they did.

Obviously, Nintendo was bothered in both of these cases because the emulators do facilitate piracy, but that's not the same as them having infringed on Nintendo's copyright by using their code which you are claiming. Both of these emulators were developed open-source; if they were built using stolen Nintendo code there would be receipts all over the place. That was never the problem.