I recently installed a Pi Zero running Pi-hole for my folks. They live in a rural area and only have a 4G Modem with a limited data plan. The issue, is that every now and then there are power outages due to bad weather.
Is there a way I can configure the filesystem so it can handle ungraceful power downs when there's a power outage?
The (native) ext4 filesystem is said to be robust with respect to power outages (ref.). I'd guess that file system corruption due to a shortcoming of ext4 is less likely than random corruption of your SD card. If that's true, consider spending a bit more for a high-quality SD card & don't worry too much about tweaking the filesystem. Maintaining a good back-up of your SD card is a wise practice also.
There is at least one technique for making the FS more resistant to corruption: mount the drive using the barrier option (see this Q&A). I'm not sure the barrier option for mounting a drive is available in the Raspbian kernel - or if it's necessary in this case, but this is a possibility if you want to do some more research.
