Stop using Facebook, Twitter, Instagram. Use Signal, try to avoid email. Use Duckduckgo instead of Google Search. Use a good adblocker. Pay everything you can in cash. Something like that?
Consider buying a cheap feature phone. Keep it turned off as much as possible. Avoid SMS as much as possible. Use other methods for calling. (Perhaps Wire…?)
Aso, consider if all this trouble is really worth it. IMHO, it’s not. YMMV.