| A few reasons: After a few years (3 if you are lucky), your phone will stop getting updates. I have a Nexus 5 with the last "official" update over 4 years ago. I have a Nexus 5x that stopped getting updates 2 years ago. https://support.google.com/pixelphone/answer/4457705 To compare, I have a laptop from 2008 (A Thinkpad x200) that runs mainline Debian no problems, and bit the thing will die before it stops getting mainline support. I want a phone where I can like that too. In all but a select, very few devices, Android is not fully open source, nor will it ever be. On a Pixel 3a, if you follow the offical compiling guide, there is a HUGE (~400 MB) vendor.img file you are forced to install, and you have to integrate several other proprietary libraries to get the Pixel 3a to even boot. On top of that, pure AOSP cripples the phone (and by that mean SMS breaks with LTE, you lose voLTE, Wi-Fi calling, etc.) A lot of Android ROMS have to scrape official images to get the binary bits (and it is nor a fun needle in a haystack excerise) to get basically phone functionality in Android. Running Android without Play Services cripples your phone in a number of ways. |
And there are aspects of newer Android versions that are less than ideal. For instance, one can see how Termux is struggling to keep working: it is not possible to run binaries that are not part of an Android package (APK) anymore. This is a security feature, but it's not always relevant depending on how you use and manage your OS.
Plus, developing for Android is a pain. You need to download, setup and use a bloated SDK with a non-free license. There's Android Rebuilds [1], but it's not complete.
I trust GNU/Linux distros like Debian, Fedora, openSUSE, Arch, Manjaro to evolve in a direction I like. postmarketOS probably too, but I'm not familiar with it as well.
[1] https://android-rebuilds.beuc.net/