The PC interface

The device that interfaces these alarm boards with my server, and my phone, is the Zooz Zen17 Universal Relay.
I chose this product specifically to interface with my Z-wave network, a low power short range 900MHz wireless network for home automation. This device is also very cheap (considering the amount of I/O and the general cost of Z-Wave devices) and can run on 12-24V DC as well as USB power.
The Zen17 has two each inputs and outputs: two line-voltage rated relays, and two sets of "dry contact" inputs (two sets of "common 0V" and "sense" pins, and when they are shorted together, the input is detected as "on".)
A useful feature of this device is that the two S1/S2 inputs can be specifically designated as generic smoke and CO alarm senors. This is set in the Z-wave configuration for the device, which I won't go into here.
By default the inputs and outputs are tied together: input 1 is triggered, and relay 1 is activated. The state of the inputs is monitored on the Z-wave network, and relays can also be triggered manually via the network (and in my case, HomeAssistant). I also changed the configuration to separate inputs and outputs, since I am not currently using the relays to do anything, having them activate with the alarms just adds uneeded wear and tear.
Here is a closeup of the relay box installed next to the UPS and alarm relay box:

With the two above configuration changes, I made two simple HomeAssistant "automations" that simply send my phone a notification when one of the alarms goes off,.
From a blank automation template:
Trigger:
 - type: Device trigger
 - device [choose the dual relay box]
 - Trigger: "Smoke Alarm Becomes Hot"/"CO Alarm started detecting gas" [choose 1]
 - Duration: 1 sec
 
Action:
 - type: device
 - Device: [choose your phone]
 - Action: Send Notification
 - Message: "SMOKE/CO ALARM HAS ACTIVATED!!"
 - Title: FIRE ALARM