The spectral sensitivity of a bare sensor can be something like 320 to 1050nm, way beyond what we can see, at both UV and IR ends. No good for normal photography so they have a "bandpass filter" to restrict their spectrum to what we expect. Normal glass doesn't pass that range well anyway.
Cheap cameras aren't very fussy. Poke a phone camera at an IR telly controller and press the buttons , and you'll see the flashes on the display.
Some iPhones at least use IR flash to recognise things to turn on - so they need a sensor which can "see" it. They're sending out light you can't see.
Some phones use a LIDAR- ish technique for depth , some go further, actuals lasers are coming in.
My FLIR camera goes way beyond what a phone camera sees. Early IR phone cameras were crap. But iPhones particularly are extending into new areas. So check their products. I expect last week's model is now sufficiently hobbled by Apple's own obsoleting software that it'll be cheap.
What really costs, in IR cameras, is resolution. You don't need it to be high for heat leaks. Mine's quite low, though it cost a lot more than it would now, back in the day. 360 x 480 or something. For finding hotspots in equipment & machinery it's fine.
If you place an IR filter over all three lenses on an iPhone 12 Pro Max, you can effectively capture infrared photography. Here’s how.
www.dpmag.com
The new iPhone 12 Pro is equipped with a Lidar sensor, marking an encouraging step towards the democratization of photogrammetry and 3D scanning. Sma...
www.gim-international.com