/ɱ/ is the rarest voiced nasal to be phonemic, its mostly an allophone of other nasals before labiodentals and currently there is only 1 reported language, Kukuya, which distinguishes /m, ɱ, n, ɲ, ŋ/ and also a set of prenasalized consonants like /ᶬp̪fʰ, ᶬb̪v/. Yuanmen used to have it phonemically before merging it with /m/.
/ɱ/ is the rarest voiced nasal to be phonemic, its mostly an allophone of other nasals before labiodentals and currently there is only 1 reported language, Kukuya, which distinguishes /m, ɱ, n, ɲ, ŋ/ and also .a set of prenasalized consonants like /ᶬp̪fʰ, ᶬb̪v/ Yuanmen used to have it phonemically before merging it with /m/.