Generally speaking, police dogs are trained to alert on command and are not used for actual investigation.
Yes, SAR dogs exist and properly trained dogs exist as well. However, the overwhelming evidence shows dogs are not a reliable tool when used by police.
Most of the airports in the US have some sort or chemical detector too. I always get my hands swapped going through PDX because I brought so scary looking circuit boards with my carryon 5 years ago.
It’s been a few years, but they are white round pads, probably 3 inches wide. I’m not sure what’s on the pad, probably a solvent of some kind.
The pads go in a machine about the size of an larger microwave oven which I believe uses NMR to scan for nitrates and other kinds of explosive residue.
It was a pair of highschool level sumo robots, lots of wires and motors and gears.