I don't underatand. You're saying people can't use PiHole with Android? But lots of people do that... Or do you mean it can't be installed on Android itself? I googled that and it seems it can be...
1. https://www.reddit.com/r/pihole/comments/18ov638/pi_hole_on_...
You still can’t set the IPv6 dns server manually and you can’t permanently disable IPv6.
When you install pihole and set it as the dhcp server and also as the IPv6 „Ra“ server the ipv6 dns server from your router will still be used primarily. Making dns based blocking on android ineffective