Pierre Dandumont uploaded a video online showing him running Mac OS 9.2 on a Wii. It's in French, so you'll have to use Google Translate to understand. But, Dandumont does an excellent job of explaining the process. As expected, the workaround isn't straightforward nor is it convenient at all.
Dandumont achieved the "impossible" by running a Linux-based OS on the Wii's PowerPC chip. As it's a close relative to the PowerPC processors used in the Mac G3s way back then, the Wii theoretically could run a Mac-on Linux. Except, Dandumont tested this theory and made it work. After much struggling, Dandumont got the Wii to run the last classic MacOS, MacOS 9. He shows off the Wii running iTunes, Internet Explorer 5, and Doom. He even tries his luck by running a MacOS X build, only to run into a brick wall. But hey, maybe another day, right?
Ultimately, the MacOS Wii is more of a novelty as it serves zero practical applications. Mac OS 9.2 looks downright ugly on the Wii and apps will crash almost immediately after you run them. You can't even enjoy DOOM on it.
It's safe to say that this is more of an academic exercise that anything else.
While we wait for someone to be able to run MacOS X on a Nintendo Wii, we can all look forward to the successor to the Nintendo Switch. Fans believe that it's only a matter of time before the next Nintendo console is announced after the existence of the long-rumored chip was finally confirmed.