Yes, it works. Connection with LAN is not a prerequisite for the function after setup. However, if the functions are to be adjusted again after initial setup, a LAN connection of the bridge is required for this, as otherwise no access can be made via the app.

I tested it straight away: The motion detector is dependent on the WLAN and the bridge. Nothing works without the bridge, even after the initial installation.
Kind regards Dänu

The motion detector itself can be set up simply like that. It is switched on, the app is started and finalised. It never needs a LAN connection. The bridge, however, always remains connected to the home network via LAN.