According to the README, it runs natively on ARM but it looks more like a program than an OS. So I'm sure it can be updated to run on Android or iOS if the GUI code is rewritten with their respective frameworks but making a bootable OS seems more difficult. The author wrote an article last year about making it a bootable OS by using a barebones x86 kernel and QEMU so I'm sure it could probably be repurposed for ARM devices. [1]
https://pmig96.wordpress.com/2023/02/24/pumpkinos-busybox-an...