MarsTrue a few steps you can take:
get a prepaid Sim and pay with cash for the recharging. also buy your phone / hotspot with cash.
untie your gsm connection from your graphene device by keeping the smartphone in airplane mode with WiFi on and using another device as a hotspot. this way you can leave your hotspot home or replace it from time to time for less than it would cost to replace your phone.
use a VPN to hide your traffic from your ISP. I use mullvad paid with btc that a buy with cash from a atm.
keep another prepay Sim in a dumbphone for activating various services that require it. don't forget to recharge it from time to time so that your number remains valid. in my county WhatsApp is very popular so when asked I give out the backup Sim number and mention that I prefer to be contacted through that app. this way I can regularly change my hotspot device and Sim without any social hassle.