Running Docker on Android is definitely not supported officially and you cannot run any official version on Android without modifying Docker or Android. So probably that’s why some people say “It is impossible”.
Other people may say it is possible, but I am pretty sure they were brave enough to change the android kernel or they found a special, Docker-like executable.
It was long ago when I tried any advanced modification on any of my android devices, but if I remember well, you can’t really change anything without rooting the phone.
Docker depends heavily on the Kernel capabilities, namespaces, control groups. As an Android developer you probably know much more about Android kernel and how the applications work and how they are isolated on Android, so if you are willing to build a custom Android kernel, you might be able to run some version/variant of Docker on Android, but I as an Android user would not try that.
I would rather try to find an Android emulator that can run in Docker containers and run everything on my PC/laptop. I guess you know about those too. I found this: