I found this thread:
https://www.eevblog.com/forum/thermal-imaging/uni-t-uni690b/I looked at the reviews for the UTI260B. Unfortunately not suitable for my purposes. First, there are always specimens that show a "hot" spot somewhere on the screen. It was not clarified whether this was due to a temp range that was too narrow (the display showed below 1°C for some) or a fault.
Secondly, there was a teardown from Fraser where you can see the greatly reduced quality of the inner workings.
Third, the start time of over 20 seconds. And when changing between high and low gain (>150°C) you can wait another 20 seconds...
Personally, the device would drive me insane. But for the price it's hard to beat. You get what you pay for. This becomes quite clear again here. The biggest problem with handheld thermal cameras is the built-in processors, and so is the cost. This then leads to such effects as a delay in the display when panning (despite 25Hz). Or how long the device boots. Mobile phone models are better because the smartphone can do all the work, including an additional strong image improvement. Or you have to spend more money.
I don't think you could set the temp range manually either? That would be a no go for me too. But everyone has different needs!
I have a HIKMICRO B20 and when I compare it to the UTI models I'm very satisfied. The quality of the inside of the device also seems to be very good. It starts within 10 seconds. and quickly reaches its final temperature. But it also costs twice as much as the UTI260B.