Yeah, this is exactly how I feel. I recently bought a new phone, and considered an iPhone for the first time. The sole reason I am still using Android is that so many of my favorite apps are only on F-droid. In my experience, open source software is far higher quality than the proprietary counterparts, but many of them are exclusively on F-droid.

> If you get enough devs creating software for the fork, you can start to get users.

Why would devs invest effort into developing for a new platform? You've hit the issue of bootstrapping two-sided markets

Most users don't know or care about this side-loading issue, and when they are informed about what it means, they definitely like the idea that the app can be traced to a real human who has been validated by their phone provider. Not having those things sounds like malware and hacking to them.

I think as per the article this couldn't be installed on Android devices though?

The people who decide platform support for major apps are usually business people, not developers. Businesses want control, which is toxic to the user. So, the only way for a new OS to get enough software support to get off the ground is to take away even more control and allow more abuses by app owners. If an OS has no user base and has pro user anti app owner security design, then very few app owners will provide apps. This problem applies both to android forks and novel systems.