The Canadian Prepper on Chris’ PREPAREDMIND101 YouTube channel compares two thermal imaging devices: The Seek ($250-$350) and the Therm-App ($950-$2,000).
Both attach to an Android smartphone, but the Seek is also compatible with the iPhone.
I consider these imagers to be gear “top-off” items. In other words, you already own almost everything else needed for a complete survival kit before you consider an investment in these units.
That being said, infrared imaging devices add a nifty addition to home and camp security: you can “see” in the dark.