If it is of any consolation, a church key has been carried by many members of the military since before WWII and well into the Viet Nam era. How else was one supposed to open a can of beer?

While the pull tab can came into being in the 60's, it wasn't universally used world-wide so there were still cans that needed a church key.
And it was an essential tool to construct a c-rat can cooking stove to burn triox or C-4 to heat c-rat entrees.
If you want a strictly US military version of a ration can opener, look for a P-38, aka "John Wayne." They're still around and usually don't cost very much even for an unused authentic USGI version.
Even today, there are still many bottles of beer that require some sort of opener to remove the cap, though in the US most seem to be of the twist off variety these days.
mreheater72 wrote:But I’m a little bit disappointed that the opener is not a "tool" for military rations

!
So long mreheater 72