I intend to put a UPS box on my CNC computer but not the controller. That way, if I have a power outage, I will have the controller return an estop and I will have a few minutes to note the Gcode position. You will also need to use machine coordinates and work offsets to reposition accurately.

I have also got a UPS for my 3D printer as a power glitch can ruin a print.

Where I live there is a tendency for short outages in windy weather.