Hello,
I have read through the statement, I understand about your requirements, A lot of ideas are revolving on my head, Please ping me for discussing the possibilities of how we can do it.
Also please note the 25 Days delivery timeline is an approximate timeline, It can be less also.
Just to wrap up, I can build you a collaborative app with Voice, Collaborative Avatar etc that can be either in AR or in VR or both.
Good luck PATH...