Was pitched Vocial - https://vocial.app/ - this morning: a social network that just uses voice.
Audioboo did something similar back in 2006 or so. I loved it - enough to be an advisor - but it never got to scale enough.
For Vocial, my advice would be…
a) base the social network on “the fediverse” - Mastodon etc
b) make Vocial a first-class fediverse client, so your friends are already there, so your posts already have an audience, and so you don’t have to actually run the entire social media network
c) make the Vocial app the place that’s optimised for voice: audio-first. The interface highlights posts made with voice (but still shows the rest). Posting voice is really easy with Vocial. Listening to it, too. But other Mastodon apps would also see the posts - just with their own clunky interface.
As a product, I think it has legs, perhaps - I suspect @evan may have views on how audio works here.