But the Fairphone 3 is running a hostile OS that has already done most of the work, and the PinePhone is still very much an early development platform.
You can install another OS if you want. LineageOS, for example (with or without OpenGApps). Or /e/. You can even buy a FP3(+) with /e/. They sell it. Or other OSes. Or you wait for FP4 which is out 25 October.
I'm not talking specifically about /e/ (though I would recommend looking into it, if you want privacy and Android backwards compatibility).
I am talking about the plethora of OSes available otherwise, such as postmarketOS, Mobian, Ubuntu Touch, SailfishOS, etc. It al runs a Linux kernel though, so anyone can pull the 'but its still Linux' card and discussion is over.
FP4 isn't even officially released yet (and when it is, there's delivery time), while devs don't get the device before release. They need to buy it just like the rest of us.
However, the previous Fairphones ran all kind of OSes, including the ones I mentioned. In fact, I believe Fairphone was the first smartphone to run on some of these (IIRC pmOS, UT).
Given the device gets support for 5 years (including software updates) that's gonna be a while where devs can support it, and where it gets (supposedly) firmware updates for the embedded chips as well.
They do. That's what Halium and libhybris are for - so you can run GNU/Linux userspace on top of Android's HAL. You can't take a mainline (or even close to mainline) kernel and boot it on these phones - or at least not when you expect them to still be somewhat useful. The mainline kernel has no support for any Fairphone at all so far (some support seems to begin appearing for FP4, but not for earlier ones).
A good litmus test on whether a device doesn't rely on Android is whether Mobian supports it, since Mobian doesn't intend to support Halium platforms: https://wiki.mobian-project.org/doku.php?id=devices (also, I just noticed that you actually listed Mobian as working on the Fairphone in one of your previous comments - that of course isn't true)
And to add insult to injury, you as the user do not get to have a root account. Yes, there are ways to get one, but even the "alternative distributions" go out of their way to make it extra tedious for you. I would for example expect a built-in menu in Lineageos settings called "enable root" that does what it says without further steps.
Instead I need do install some 3rd party stuff from somewhere, get the bootloader image from somewhere, patch it, use a PC to install that image... for each update!
In theory, sure. However, having done that dance before, the limitations between a degoogled Android (basically open source apps only, since F-Droid doesn't allow proprietary apps, and nearly all proprietary apps depend on Play Services APIs anyways), you end up with something less useful than a PinePhone.
And at the end of the day, Android was written by Google for Google to serve Google. Trying to use a phone as your daily driver running developed by your enemy is hardly a way to get through life. Just get a phone that doesn't hate you. Like a PinePhone. Or an iPhone, which has all sort of issues but at least gives you a reasonably private and secure device at the expense of gobs of money.
MicroG may still ping google services sometimes, but it is not a root level backdoor into my phone. Most proprietary apps I've tried work. Bank app, dating apps, slack, visual voicemail, venmo.
