Yuzu uses Unicorn, which uses QEMU code for functional, but not cycle accurate CPU emulation. Most software these days don't depend on the exact behavior of the hardware, even on Nintendo Switch, and the emulator can also use application-specific patches to make up for the difference.

86Box is not entirely cycle accurate, but much more accurate than QEMU, so no patches are required.

gem5 is on the other end of the spectrum, it can emulate hardware very accurately, but very slowly.