en.wikipedia.org/wiki/Lakota_language#LLC_alphabet

The consonant chart gives the Lakota spelling of /ŋ/ as ⟨ň⟩, but authoritative Lakota orthography references use ⟨ŋ⟩ instead.

Unicode’s Lakota character guidance lists the non-English Lakota consonants as č ǧ ȟ ŋ š ž, and its standard digraphs include aŋ, iŋ, uŋ. That is the current standard character inventory for Lakota, and it does not include ň for this sound.

Unicode’s code chart also notes that Lakota historically used ƞ/Ƞ to indicate nasalization, but that usage was superseded by ŋ/Ŋ. So even the older special Lakota letter was ƞ, not ň.

Because the article’s own orthography section later uses ŋ (for example in aŋ, iŋ, uŋ), the ⟨ň⟩ entry in this consonant table appears to be a mistaken character substitution rather than a valid Lakota spelling.