Earlier quoted context omitted.
I'm mostly interested in the CAT as my job (research) involves a lot thermal imaging, so there's a nerd factor (the lepton on its own is about £3-400 with a capture setup). I know there's also the FLIR One, but eh, for field work the CAT looks handy with the extra sensors. The light phone looks good, but I do actually want some of the smartphone features. I was very unhappy when Amazon nerfed 3G on Kindle, I used to…
I got a stand-alone FLIR for that purpose. Though there's also some which you can connect under a camera via USB-C/microUSB/lightning. Everything on the same physical device has its own pros/cons.
The FLIR One comes in a USB C model, I've played with that on my Pixel. Works great although I think you have to use the sdk to get any kind of useful information out of the camera (eg if you want raw data).
My group specialises in drone imaging and often it's useful to have ground footage so you can compare simultaneously, for example during biodiversity surveys. The problem with the plug in solution is the risk of it getting lost in the field, and it's not rugged enough. We recently did some surveys on a lake, so an IP rated phone with everything integrated would be ideal.