Backup Power for Intrusion Detection

Been using HE for a few months now, have a nice z-wave plus network consisting of several Inovelli Switches, and a few plug-in repeaters (Aeotec Range Extender and Siren 6's, GE outlet plugs). Have several battery powered motion sensors and battery powered contacts on all the doors. My goal is to provide a UPS type battery backup solution for if the power goes out, so I can just maintain HSM for intrusion detection and firing off a siren while I am home. Think scenarios such as bad guy flipping the main breaker for the house, etc....I want to have some warning once intrusion occurs and i need to act. I know not all of my contact sensors, and maybe even not motion sensors, are able to reach the hub without taking a hop or two, so would it be easy to hook up a couple repeaters into their own UPS batteries, say one on each end of the house? Also how will hubitat handle being on a UPS, will the transition be seamless to battery power once power goes out? I have never used a UPS so I am not sure of their capabilities.

Another solution I am willing to consider is not using the z-wave network as far as a security system and getting a standalone security system with battery backup, that doesn't require repeaters, and I could integrate this new system with Hubitat. My understanding is that most of the better systems (not ring, etc) have sensors with much better transmission power thus not needing repeaters. Ideally if I could use the new system's wireless sensors for all of my HE automations (through an integration) this would be ideal. Wired sensors are probably out of the picture as our upstairs is not going to be renovated anytime soon (basement is unfinished though).

I imagine you could use of one those portable phone charging batteries that allow passthrough of power.

Some allow the battery to charge at the same time as the daisy chained device.

This is the smartest route you can go. Integrate the systems but don't think of Hubitat or any Home Automation system as a "Security System". I'm a big pusher of the ELK M1 security system because it's integrated with every major automation platform and I think there's a Hubitat app even (maybe?). Another good system you can integrate with is a DSC Alarm panel and they are cheaper than ELK.

I'm sure the first thing everyone else is going to point out is that neither of these systems are cheap. No they aren't. They work!