A conlang I am working on contains the nasal syllabic consonants [m̩] and [n̩] fairly frequently. It seems like it would be a natural step for the language to develop what I would call a voiced velopharyngeal stop occurring before those syllabic consonants are used some of the time, to add emphasis. This stop is formed by stopping air from flowing into the nasal cavity with the velum while the mouth is in position to form the following consonant, and then releasing it into the nasal cavity. Think of it as trying to make a “g” sound through your nose only.
Ex: [ĩɲ'tⁿn̩] => [ĩɲ't̚?ⁿn̩], where the ? represents the consonant in question.
Note: This is not a glottal stop, though that sound can occur as well in this language.
I have been trying to transcribe the language with the IPA since it helps specify pronunciation of the weird vocabulary of sounds, but I cannot find a symbol in the IPA that represents this sound, even though it seems to me fairly plausible for a language of this type.
The closest I have found is the symbol for a velopharyngeal fricative [ʩ] in extensions to the IPA. However this still is clearly distinct from the sound I am describing. Additionally, it appears to only occur as a speech defect and never as a proper consonant in a language.
What is the best way to transcribe this specific sound using the IPA? Is there an allotted symbol that I just could not find? What would be the best way to go about phonetically transcribing the sound if there is no exact symbol in the IPA? Is there a better approximation than [ʩ]? Additionally, what about the unvoiced counterpart?
I apologize for any mistakes in my use of the IPA, I am still learning.