It is an absolute nightmare, but you can gain some privacy back with ublock origin, an adblocking DNS on your phone, Firefox, a VPN, and ditching all things google/meta. As I type this out, I am reminded how much effort it takes to claw back your privacy…yeah OP, I’m with you, the modern internet is a profit-at-all-cost cesspool that can eat a moldy potato!
You have to accept that privacy costs money because your data isn’t being sold. For $5+ a month you can use proton Mail or tutanota. For ~$2 a month you can use Zoho mail or Titan mail.
Whatever you choose, it will be worth it.