In my experience the industrial FLIR cameras that I have used always enhance the zoomed image. That is to say they take the reduced number of physical pixels in the zoomed image and interpolate them back up to the cameras full resolution. I did some tests on my PM695 switching between using a close up lens at 6" distance and a digital zoomed image from a greater distance without the close up lens. The FOV was approximately the same in both cases. I was surprised that I initially could not see the normally lower resolution, more pixelated, zoomed image. Both the close up lens and digital zoomed images looked similar. The reason was the zoomed image had been interpolated using a decent algorithm and actually looked very good.
In addition, many FLIR industrial thermal cameras offer constantly variable zoom instead of just stepped X2, X4, X8 zoom. The Interpolation algorithm must be pretty sophisticated to cope with captured image to display resolution mismatches.
Fraser