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.
Speaking from experience, I’d recommend not choosing protonmail because it is very difficult to cleanly stop paying and leave - forwarding mail to another address is a paid feature. It’s also not very standards compliant (no IMAP/SMTP support without running a buggy bridge). Their security features are mostly useless and better security can be achieved on standards-compliant services if you try.
Buying one or more domains and using those with protonmail gives you 100% portability. Just redirect your domains to a different mail server if you decide to make a switch.