[SheinhardtWigCo]

I worked on something very similar: a privacy-first Instagram clone built on top of Matrix. We had a prototype and some initial users.

Here's the unfortunate truth:

The challenge of overcoming the network effect is _the_ problem you're solving here. Nothing else really matters. Almost nobody will care that it's privacy-first. Asking HN to help you figure this out indicates to me that you should do something else.