Fairphone with custom-rom is a great sustainable and independent possibility. (Maybe tricky to buy from US).
Pixel with custom-rom grapheneos is a very secure possibility.

@waldschnecke

@synapsenkitzler @waldschnecke What would be a recommended custom ROM? Is there anything actually close to GrapheneOS?

@frdnd @synapsenkitzler @waldschnecke

There is currently no custom OS that comes close to GrapheneOS. GOS is currently the only custom OS that maintains the security of AOSP and releases security updates on the same day they are published (by comparison, with IodeOS and LineageOS it can take a few weeks, and in the case of e/OS/ a few months).

They also significantly increase the security of AOSP:

https://grapheneos.org/features

You should take a look at eylenburg's comparison table, which provides a clear overview of important information about the individual custom OSes:

https://eylenburg.github.io/android_comparison.htm

GrapheneOS features overview

Overview of GrapheneOS features differentiating it from the Android Open Source Project (AOSP).

GrapheneOS
Android: GrapheneOS, CalyxOS und Co. unter der Lupe – Custom-ROMs Teil1

In der Artikelserie »Custom-ROMs« werden bekannte Vertreter auf ihr Datensendeverhalten überprüft. Vorliegend wird das Testsetup beschrieben.