[Sophira]

While the OOBE of the stock image doesn't force an Internet connection, the ability to unlock the bootloader does - whether you can do it or not depends on the phone manufacturer's desire, and Android for some reason uses an Internet connection to check that.

My understanding is that it is impossible to unlock the bootloader on a new recent (Android 7+ at least; possiblt earlier) Android phone until it has connected to the Internet. After that, the ability to unlock the bootloader is permanent.

[dlenski]

Yep, on older phones it was certainly possible without an Internet connection.

On the Nexus 5, you could just `fastboot oem unlock` right out of the box, install TWRP (custom "recovery") and install CyanogenMod/LienageOS, without ever booting the stock ROM.

On my Moto G4 Play and Moto X4, you had to get an unlock code from the Motorola website (based on the phone serial number I think) and waive some warranty terms, but once retrieved at least the phone didn't need to be online to unlock the bootloader.

The process on the newer Pixels is disappointingly intrusive, like basically everything Google has done for the last decade.

[Markoff]

If it is any consolation it became intrusive on pretty much every single brand nowadays, if they at least offer bootloader unlocking option.

[Sophira]

I misspoke when I said Android 7+, my apologies; I was thinking of my Pixel 7, which runs Android 13.

[Markoff]

it should be possible on Sony and OnePlus phones and maybe other brands, though it can require obtaining code from internet on other device, but the device being unlocked itself doesn't need to have internet connection

[a96]

I think LG had a system for getting unlock codes as well, but they closed it a long time ago.

Any other manufacturer may alter the deal any time. In case you have such a phone, dear reader, consider getting your code if you still can even if you won't use them yet.

[Sophira]

...I feel a bit silly. When I said "Android 7+", I was thinking of my Pixel 7, which runs Android 13, so "Android 13+" is what I actually meant to say. Oops.