Looking for battery monitor

I have been looking and am unable to find a device that isn’t too expensive, is low on the diy time investment and works with openhab.

I like this one

The price is higher than I like, but I can go with this. I can’t get any info from the company if it will talk via some API without the phone app.

I have various battery powered vehicles and devices that i’d like to monitor so that I can put them on a charger before the batteries are damaged.

I would love a tasmota device on wifi. But would settle for zwave. My current thinking is too get a dozen zwave door sensors. Put in a large capacitor in place of the battery and charge it with a voltage divider resistor pair. When the sensor reports its battery level, I can use rules to alert me when a battery needs charging.

This device could use several tens of milliamps, and would be acceptable.