If for some reason you don't like the look of NUT, and you get an APC UPS (and maybe some others?), there is always apcupsd. It will run shell scripts upon certain events, etc. Old, simple, works.
I've lived in areas where Comcast stayed up during long outages and areas where it didn't. Not sure about FTTN, but I don't think consumer broadband services are required to stay up during an outage like copper phone service is.
I only own the gear marked A and B, which lives above the couch I call home.
A is my web services 24/7 Proxmox box, an Intel 8500T; 2 routers; an 8TB HDD; and a Back-UPS Pro so old its ethernet surge protection is rated for 100bT, with a brand new LFP battery in it. The UPS powers both A and B.
B is my personal Proxmox box, an AMD 5750GE, which I use for development and running desktop OSes which I remote into, plus a GL.iNet Slate AX router. These come with me if I stay someplace other than the couch (not pictured). That's why they're on different shelves. Also, there's a USB wifi dongle w/antenna connected to B which I used when some stupid website demands I drop my VPN (all traffic from everything pictured is routed thru 24/7 private VPN endpoints, aka a $2/mo VPS or three).
If for some reason you don't like the look of NUT, and you get an APC UPS (and maybe some others?), there is always
apcupsd. It will run shell scripts upon certain events, etc. Old, simple, works.