I've only ever found those to be simple physical switches. I use a spare credit-card sized object from my wallet, e.g. a loyalty card or an enomatic charge card

I've only ever found those to be simple physical switches. I use a spare credit-card sized object from my wallet, e.g. a loyalty card or an enomatic charge card (I have a half dozen of these), but even a stiff business card will do if it's the right size. With far less attention to security, I do this to e.g. charge up devices while I go get a bite to eat before heading out again in the evening.