HA startup/shutdown complete on Raspberry PI

I am very new to Home Assistant and RPI. I am interested in potentially integrating HA into one of my products as a means of providing a voice control interface for the project. I have a prototype set up and working nicely. My product is an outdoor application, and it does not run continuously. It’s more like turn it on, use it for a few hours, then turn it off and bring it inside. I am looking for a way to power it down gracefully so as not to corrupt the SD card. HA can be shut down using the web UI, but there will be no display to determine if the shutdown process is complete. RPI is just a headless CPU acting as the hub.

Is there some way to program/configure a GPIO pin outside of HA that can be wired to an LED?