Android is a Linux phone but it’s decidedly not open.
Another Unix would be ok as long as it's not hidden away under a forced UI, with some things unconfigurable, required, etc.
But ultimately I want to share dotfiles between my desktop and phone (sure I might have to accept some amount of conditional guards..) - and that pretty much means Linux and ideally Arch. But only because that's what I happen to use on non-phones.
I wish something like CloudAPI/Capsicum would take off to be more secure, while also being an open platform, instead of Linux ubiquity rendering standards irrelevant.
I didn't understand why it's so important for it to be Linux, as opposed to any other operating system that's as hackable/customizable. So I wanted to know if I had missed something.
I should apologize for my response then. I'd thought you were alluding to iOS, and thought that it was strange to bring that up when discussing configurable OS's.
As it is now, the PinePhone is officially supported by Manjaro and that makes it the most obvious option. Also, all attempts thus far to bring open source to mobile has been some form of Linux, so it's natural that when people think "open source phone", it's probably going to be using Linux. PinePhone itself already has 18-ish different distros, including ports of Debian and Ubuntu, so it's certainly well on its way.
I like open source too, but I'm not serious about it, I want to be able to fix things or file an issue on GitHub or whatever if necessary, but I don't have the energy to worry about proprietary blobs.
Having control of my phone and its configuration like I do my Linux desktop is what I want, but I'm slightly resigned to perhaps not getting it because of app support (I tried Anbox on my desktop, it was buggy and slow, with a fraction of the RAM I dread to imagine) - so I've been thinking about and occasionally working on a Terraform provider for Android instead. So far I'm using it to install all apps, no Play Store at all; I'd like to have it handle settings too.
So yes, it is Linux more than OSS that appeals to me here, because it's control more than openness that interests me in it. (I suppose some wouldn't see a distinction, and that's partly why it is more important to others.)