Custom Android ROMs based on AOSP, which is the open source parts of Android. I used to use LineageOS back in the day.
Before buying a phone, make sure that it has an unlockable bootloader and a custom ROM of a recent Android version. Note that some phones have multiple versions for different regions and some might not be unlockable, while others are. For example many Samsung international phones are unlockable, but none of the USA models are.
Note that many commercial apps like Netflix, Pokémon Go, bank apps, etc. will refuse to run if your bootloader is unlocked. It also permanently trips Samsung's Knox.
Custom Android ROMs based on AOSP, which is the open source parts of Android. I used to use LineageOS back in the day.
Before buying a phone, make sure that it has an unlockable bootloader and a custom ROM of a recent Android version. Note that some phones have multiple versions for different regions and some might not be unlockable, while others are. For example many Samsung international phones are unlockable, but none of the USA models are.
Note that many commercial apps like Netflix, Pokémon Go, bank apps, etc. will refuse to run if your bootloader is unlocked. It also permanently trips Samsung's Knox.