I don't understand why no one mentions SailfishOS. It's an alternative that is available right now.
Sure, it's not up to the level of Android and iOS in most respects, but it takes effort to get something like this going. Also from the users. Like Linux 20 years ago.
Developing for it is not a nightmare either.
And it's running Linux so there's advantages as well.
I used it as my daily driver years ago and I've been using it as my daily driver again since six months or so.
I've looked into Sailfish before. Isn't it closed though? (It might have a Linux kernel, but that doesn't mean the rest is open) and as far as I can tell, it's not (easily) available in US markets.
It's not as open as the Librem phone, I think. What do you mean with "open"?
What I meant to indicate is that it is a viable alternative to iOS and Android, available right now. (Except it's hard to get outside Europe, China, Russia and India apparently. I missed that.)
I ordered a new old-stock Nexus 5X to run KDE Plasma on. Fuck both Google and Apple. I hope the Purism and Pinephone actually get released as well so we have more real Linux options.
I hate we live in a world with totally non-standard mobile hardware. Back in the day you could wipe Windows and run Linux on nearly anything. Maybe you would only get VESA graphics or text, but it would at least boot.
PostmarketOS is trying to make a dent in it, but we still have huge gaps in hardware support.