You can (on most Android phones) run an Android fork that doesn’t have Google services running and gets software and updates from elsewhere, e.g. GrapheneOS. Can’t do that with an iPhone. I get that you’re still ultimately dependent on Google to continue Android development and make security updates, but it’s way less of a dependency. And yes, GNU-ish Linux on phones would be awesome.
Yikes. While shopping for a new phone last year I was under the impression that at least in the European market they still allow you to unlock the bootloader, even on the latest models. The catch is that there’s pretty much no third-party Android distros that work with the phones, because they don’t release drivers or kernel patches and people have to scrape them from first-party OS images, which sounds horrible.