Shutdown service for RPi load

I made the move from DD-WRT about a year ago specifically for DSA to support a need for Dumb APs backhauled to a pfSense router. Took some time but it's working exactly as expected. Thanks to all who worked on the DSA piece!! So, when I saw there was a Raspberry Pi build, I decided to spin up a travel router with a solid firewall, VPN and a bit IPS/IDS. Everything seems to be working fine but was curious. I know most of the plastic box routers intended to use OpenWrt just have a power switch and I'm not sure how OpenWrt handles open files in a power shutdown operation...

So my question, is there a need to use something like the "plymouth-poweroff.service" and if so, has anyone written a script or package to install/utilize it?

Yep, I use the "Advanced Reboot" package for my Dumb APs (WRT3200ACMs) and know there is a "perform power off..." button there. While it works on my Dumb APs, it doesn't seem to have any impact on the Raspberry Pi... ie: an SSH session remains active.