It is not possible to download or install a "signed iOS 9 ZIP" directly onto an Android device to run the iOS operating system.
This is not for end users. It requires termux, proot-distro, and compilation experience. Download ios 9 signed zip for android
not possible to download and install a real, functional version of iOS 9 (or any iOS version) on an Android device It is not possible to download or install
Regarding iOS 9 specifically:
If you tried to force an iOS 9 IPSW onto an Android phone, the first line of code (the bootloader) would reject it instantly. The Android bootloader expects a certain format (like boot.img with an Android header), not an iOS iBEC or iBSS. not an iOS iBEC or iBSS.