What are Virtual Devices used for?

It s little more tricky.

One thing to add:
A flow can be triggered with the default trigger-cards ‘mode on|off’ or the custom trigger cards: ‘mode is on|off’. They work similar, but the big difference is that the custom trigger cards are not triggered when the mode is set in another flow with the action-cards ‘Set mode on|off, no trigger’.

Apparently, there was a bug initially, but now it seems to work as intended:

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