What does “no neutral” mean?
The wiring in your switch box determines your options.
A switch box can differ
Some switch boxes contain no neutral conductor. A suitably qualified person should identify the wiring; do not rely on colour alone.
Buy the exact version
Only select a no-neutral model when its documented supported loads match the light circuit. Minimum loads and compatible lamp types vary.
Plan the network
Many no-neutral SONOFF relays use Zigbee and require a compatible coordinator. Verify hub support before ordering.