Some of us are already doing this. My main phone is a Google Pixel 8 running LineageOS 23.2 with F-Droid, microG, and Aurora Store installed.

For things requiring Play Integrity, I picked up a $20 burner carrier-locked Motorola phone at Walmart for $30. It's WiFi-only, given that I'm never going to pay for service on it, but I can also tether it to my main phone. It's also useful for writing one-star reviews on apps that require Play Integrity to function, which is something everyone should be doing.

>For things requiring Play Integrity, I picked up a $20 burner carrier-locked Motorola phone at Walmart for $30.`

So it's a $30 burner phone, not $20?