Cell towers can use the SIM card to track your IMEI number which is specific to your device and may link to your identity depending on how you purchased it and your carrier.
Generally there’s no perfect solution to this short of not using a phone. But as a compromise some people opt to never add a SIM card and instead keep their device WiFi-only while always using a VPN, MAC randomization on in settings, and airplane mode.
Some apps such as simplex allow you to sign up without a phone number for your texting & calling needs. Of course it’s not perfect and I assume almost anybody would want a real number somewhere (perhaps on a different device or landline).
For me it’s reasonable to not have cell service on this phone because it’s only one of several phones I own.
Thanks anyway, it’s good info for anybody reading!