Just my two cents on this topic: I used to use an Android phone with LineageOS (this was before Graphene was a thing), and struggled with similar bugs/issues from time to time.
I got an iPhone and never looked back.
Don’t get me wrong, as you suggested here, iPhones are objectively worse in a lot of ways. But mostly, it. Just. Works. And, rather than fight the OS on things like VPN configs, ad blocking, browser usage, etc, I’ve found that I simply use my phone less, and tether my phone to a real computer more often. Paired with a small chromebook or other laptop running Linux, or (gasp) even MacOS, I just don’t use my phone as much as I used to.
On the plus side, iPhones are supported for a long time, have a secure lockdown mode which you can enable if you’re extra paranoid, and have “don’t need to think about it” full-device encryption including full phone backup support. If your phone ever dies or you want to upgrade, you can load a full backup/image from your old device on to your new one with close to zero fuss (just gotta deal with USB 2.0 speeds on all but the newest phones :)
One final note, you don’t need to sign in to an account to use iOS as far as I’m aware. You lose out on the sync/iCloud stuff that Apple provides, but it sounds like you don’t care much about that anyway.
Yes.
I’m not even sure I know what “as anti-privacy as possible” actually means, but this is a garbage statement, and I say this as someone who thinks that both Android and iOS are flaming piles of shit. Did you see that the OP mentioned that they’d consider switching to an iPhone?