The use cases described are niche enough that iOS users can buy a second Android phone to use it with.

I think activists and journalists will make the sacrifice considering the nature of what they do.

like what? Feel free to post your preferred messenger that works p2p without internet.

Scuttlebutt works over wifi, tor, internet, sneakernets, etc. There is an android client called Manyverse; a desktop app, a cli client, libraries in Python, Java, NodeJS...

iPhone makes much of these concepts either impossible or extremely difficult.

Namely, things cannot operate easily as a background service. Forcing the user to jump though many hoops to make it work. And since it is not an apple service. There is a single button "reset settings" that breaks all the users changes for these apps.

On one hand it is generally more secure for iPhone users, on the other hand it greatly inhibits some types of innovation.

I understand.

But it doesn't change the fact that other tools are available which do serve both and are thus much more practical.

There are no other tools that are as quite as paranoid as briar.

There is a severe usability and practicality hit as a result. But if you have friends who interested and paranoid then it is quite worth it.

In other words, this is a very limited, niche market product.

Well yes, being an activist or paranoid of the government isn't for everyone.

One definition for the word is "Anything that is produced". So yes, all software is a product.

Yes I wouldn't touch it because even though I'm not into Apple and its ecosystem I do communicate with Apple users and I'd expect activists would want to too.