Request for military-themed emojis on iPhone

Apple is not responsible for emojis, the Unicode Consortium is.

You can submit ideas here -

https://unicode.org/emoji/proposals.html

The reason why the Unicode Consortium is responsible for emojis is so they are compatible across all devices. You would not want to send an emoji on one device that would appear as something completely different or not at all on another device. They are not pictures that are being sent, they are similar to a letter/number typed on the keyboard.