The secondary side of the transformer supplies 24V at max. 0.83A - the magnetic switch could be used - but for what purpose? If you want to light something like a cupboard or a chest, there are better and cheaper solutions that come with a contact switch (or motion detector).
The Lightstripe from Philips only works properly with the Bridge - without it, you can only switch it off by unplugging it; other settings are not even possible. The warranty would certainly expire if you had to cut the cable.

My recommendation: LED light with motion detector (https://www.digitec.ch/de/s1/product/x4-ledstreifenkomplettset-bewegungsmelder-stecker-cm-warm-240cm-warmweiss-led-streifen-10056323)

Alternatively, buy a Phillips hue Bridge (https://www.digitec.ch/de/s1/product/philips-bridge-leuchtmittel-5628454) for the Lightstripe with a motion sensor (https://www.digitec.ch/de/s1/product/philips-hue-bewegungsmelder-leuchtmittel-5893079) - then you can use all functions and define entire lighting scenarios :-)