Long ago I used a system called hushmail that promised a lot of the same as proton. Eventually I set up my own but it still has the problem of having to relay outgoing external mail through another box because of all the restrictions on home based dynamic IPs, so it's largely relegated to system alerts in house rather than general use.
It's a balancing act to be sure. VPNs stop local ISP inspection in exchange for potential viewing by the VPN host. DNS filters can only filter known threats. Things like P2P private nets can be infiltrated by 3rd parties via the '6 degrees of separation' premise or even tracking pixels.
Making the picture muddy is about the best we can do, but it's always worth the effort to not be another data point in the profile machine.