Just as an FYI: PF2M's website is currently down, and that includes his Mii grabber under pf2m.com/mii. Whether as a consequence of this or not, setting Mii profile pictures using NNIDs does not work now, so moving forward you will have to use an image of your Mii, a Mii Studio Mii (which allows your Mii to use different reactions), or another profile picture. Those who already use NNID Miis as their profile pictures should be able to use them as normal. If you want to access Miis from NNIDs, you have several options. You can first see if your Mii is saved under https://savemii.rixy.eu.org/ (though it only has ~17000 NNIDs). You may also search up a user on Archiverse (https://archiverse.app) based on their NNID, and it should display their Mii.