Thanks to an esteemed AK member, I have a couple of packages of them.
Thanks to -- who knows what provenance -- I still have a flash gun that uses them.
... plus, I remember using them in cameras from my childhood -- up to and including the famous Instamatic "flashcubes".
(they may have used zirconium rather than magnesium, but I am not at all sure)
I may have some Flashcubes, and I have a couple of Instamatic Cameras (the 100 actually used individual bulbs!) -- but, of course, no 126 cartridge film to use in them!