Well, not sure if they're designed for it or not, but I've seen battery packs that let NFC go through, and the S7 Edge one (the wireless charging pack) lets both SP and NFC work, but they do so with a diminished range. Wireless charging is far more sensitive to added distance or bulk between the transmitter and the receptor coil, though, so that's why you'll see that feature fail a lot more with simple plastic cases that are too thick. NFC and SP's MST are a bit more powerful and can work even with those 'obstacles', even if not as easily.