As soon as you connect a phone to your home WiFi or log into a single account that device is instantly associated with you and tracks you forever. Phone numbers are just a convenient way for big tech to share your identity amongst themselves.
Use a VPN and try to create all of the accounts you'd need to participate in society. It's impossible. You'll be lucky if you can get an email address. I can't imagine being un-banked or unable to afford a phone. You can't participate in modern (western) society without a (non-VOIP) phone number.
Also, there's no air gap on a phone. Devices will be correlated via location data, SSID scanning, etc.. Put two devices in the same house with wifi disabled and location data enabled and they'll be instantly linked as knowing each other.