Would this work with any metallic phone or case.?
Many metal cases or components will interfere with the qi-style charging coils. If the case is rated for MagSafe compatibility, then it should be fine.
For other phones, like iPhone 11 or older, or many Android phones that can do wireless charging, you may still be okay, but it’s very much up to the user - I used some Mophie and other magnetic alignment rings (from Woot, Amazon, and BestBuy) and have pretty decent charging on one older iPhone for me, as well as my older Pixel. Just trying to align it without those stick-on rings was always a pain for me, so I would personally only choose to apply a magnet ring, or use a different style of wireless charger, or even wired connection.
This is really designed for Apple’s MagSafe, so that is really the benefit… That mostly means Apple, or some of the newer Qi2 compatible devices. Or “hacking” together a solution like I mentioned I did.
Hope that helps.