Shelly Dimmer 2 and Shelly 1L can be run without zero / neutral conductor.

For it to work, a minimum load / lamps or a Shelly Bypass is required;

Shelly Dimmer 2: at least 10W

Shelly 1L: at least 20W

To run these devices with a smaller load, a Shelly Bypass can be used instead. It is connected at or on the road to the load / lamp. Shelly Bypass is connected over (parallel) with the load / lamapn so that it can pass a small current to drive the Shelly unit.

Shelly Bypass can also be used so that the unit does not turn off if the lamp breaks. Maybe you use a button to control scenes or have an automation that detects if the lamp breaks.