Comment by DesktopECHO

I went the Linux Deploy route and published a couple of container images that Just Work on pretty much any ARM Android device.

Once you shiv systemd, some pretty elaborate scripts can run in an Android chroot just like they would on bare-metal ARM. Just think of your old Android as an off-brand rPi with case, built-in touchscreen LCD, and way, way fewer GPIO pins. No surprise the server will need a new UPS battery.

NextCloudDroid: https://github.com/DesktopECHO/nextcloudpi Pi-hole for Android: https://github.com/DesktopECHO/Pi-hole-for-Android