The Pixel is a good phone to test the latest android features for development purposes. I would imagine to some degree they are trying to target developers interested in testing software by offering the ability to unlock and relock the bootloader. This fosters a vibrant developer community and encourages innovation. Certain things can be tested in an android emulator but it helps to have a real device to test as well.

Pixels often ship with hardware features that other phones later include. For example Pixel 8 was the first phone with hardware memory tagging extensions and if developers wanted to test that feature they would buy a Pixel first and then use that experience with the devices their company is manufacturing. Pixels are often released with new android versions that implement android features and APIs the way they were intended to work. There have been cases of OEMs releasing devices with broken implementations of standard android features.

Pixel was the first phone with Strongbox as well. Additionally, It was the first android phone with satellite connectivity.

It also attracts the segment of the market that just enjoys modifying their phones as well. So basically they are targeting the power user community and developers. Despite the Pixel having the ability to install custom verified boot keys and custom OSs, Google knows that very few users use those features so it does not cut into their Play Store and Play Services market share very much.

The legacy SafetyNet check bypass may not be around much longer especially because hardware based attestation will be gradually replacing it.

https://grapheneos.social/@GrapheneOS/111504057847795464

Below is a guide for app developers who want to support third party OSs in a way that does not rely on Google. Most apps work on GrapheneOS just fine already but there are some banking apps and NFC payment systems that do not.

https://grapheneos.org/articles/attestation-compatibility-guide

Schools even have Cellebrite devices now, that is how prolific they have become. GrapheneOS has a duress password to wipe the phone and you can block all data or even power to the USB port while the phone is running. If you blocked all power to the USB port while the phone is on the only way to charge it is if it is fully turned off putting your encrypted data at rest. You can just disable data on the USB port options menu in GrapheneOS if you don’t want to completely turn off the whole port.

You probably already know this stuff I was just mentioning it for people reading this comment section. :)