If you really want to try the pihole, and are worried about corruption you could use a read-only root filesystem and mount /tmp and /var/log on tmpfs ramdisk, a

If you really want to try the pihole, and are worried about corruption you could use a read-only root filesystem and mount /tmp and /var/log on tmpfs ramdisk, alternatively, add "@reboot touch /forcefsck" to force a disk check whenever the Pi(s) reboot, including when power returns after an outage.