Actually… It is possible. But you have to use the IFTTT integration, just as you would with echo.
On the SmartThings side, you assign a virtual switch to run a routine, and that routine can change the mode. Or arm smart home monitor.
Then you have your IFTTT applet turn on the virtual switch when the pop button is pressed.
Here’s the FAQ for how to do that. Although this is discussing echo, it’s the same process for the pop switch.
Of course this assumes that the IFTTT pop service/channel is available in the UK, and I haven’t confirmed that. please let us know if it isn’t. The UK page I link to above which describes the specifications for the pop switch does say it has IFTTT integration, so it should work.
