Niger → Germany
Niger plugs
Type C
Type EGermany plugs
Type C
Type FShared plug type: C
Compatibility: Compatible
Voltage — Niger 230V — Germany 230V
Voltage is the same. Your devices should work normally.
Device compatibility (phones)
Phones almost always support 100–240V, so yours should work safely. Check your charger label to confirm.
You likely only need a plug adapter (if socket shapes differ). Voltage is close between these countries.