If you're serious about this approach, the best option is (ironically I guess) just buying a Pixel device directly from Google. They tend to be well supported b

If you're serious about this approach, the best option is (ironically I guess) just buying a Pixel device directly from Google. They tend to be well supported by third party ROMs and are easy to root or flash. You can also grab a used device with a confirmed unlocked bootloader. You usually have to ask a seller, and some won't know the answer, but you can provide the steps for them to determine this.