Compatibility summary
Your Thailand plug may fit in Niger outlets, as both use at least one common plug type.
Plug comparison
Thailand plug types: A B C O
Niger plug types: C E
Both countries share at least one plug type (A B C O and C E), so some plugs may work without an adapter. Check your appliance.
Voltage comparison
Thailand: 220V, 50Hz
Niger: 230V, 50Hz
Voltage difference is within a range many devices tolerate; check your appliance label.