My personal experience. I've been using GNU/Linux on my daily driver phones for nearly two decades now. Started just before the first Android phone appeared on the market and went through a bunch of devices since. Android never appeared to me as a viable alternative during that whole time (it was in fact closer to being one in the past than it is now) and iOS has just never been something I'd like to use.
I have listed several reasons why I think so in other threads here already, but the main thing is that what I longed for in 2008 when I was getting my first smartphone was a connected personal computer that I can put into my pocket and carry around through a day, and that's what I was always getting with GNU/Linux phones, so I never really got used to the idea of smartphones as these limited, mostly vendor-controlled devices that effectively serve as a trusted runtime environment for adversarial software (and by "trusted" I mean trusted by apps, of course). Instead, I see my phone like I always saw my GNU/Linux PCs - as a tiny box full of useful tools that are there to serve and empower me to reach my goals and which I can put together and modify any way I like to. May not have the sleekest design out there, may not be a speed demon, may have a quirk or two to tolerate and may require me to scratch some itches by myself, but it does what I tell it to regardless of whether it's aligned with some corporation's interests or not and it's well worth the effort spent to configure it to my liking. It's also generally a wonderful thing to tinker with (though this mattered much more when I was still a teenager :))