How does one minimalize privacy concerns on SIM cards and phone numbers

What specific privacy concerns do you have? What is your threat model? Linking you between services by databrokers, sim swapping, data breaches, cellular tracking? It could be beneficial to use a consistent phone number between financial institutions because they will already share the data all around and it could help you use those services easier, they might treat you nicer. If you are just signing up for sites that ask for a phone number once you could use SMSPool.