Add a smartphone power bank as UPS. Simple, cheap and sufficient. It avoids the need for OH restarts every time you or someone else hit the breakers or earth (ground) cable. I stopped counting how often that happened in my house over the last year.
Moving away everything from SD card is possible but don’t focus on that, it has drawbacks, too, and even if done properly, it’s not sufficient.
What’s much more important is a plan for quick recovery. See my recent post here and also this old one.