It could also contain non-public domain data, and you can’t declare someone else’s intellectual property as public domain just like that, otherwise a malicious actor could just train a model with a bunch of misappropriated data, get caught (intentionally or not) and then force all that data into public domain.
Laws are never simple.
Pixel 7 is going end-of-life in 2028 while Pixel 8 will reach it in 2030. It’s up to you to see if you think you’ll make either last until that time and if the extra $100 is worth the two years of security updates or not.