What protection? What privacy? Smoke and mirrors, mostly.

NAT is a firewall with extra steps. IPv6 reduces complexity. Privacy (illusion of it, anyway, just like in ipv4 NAT) is handled by private addresses.

…and if you really want to, NAT for ipv6 just works.

NAT is not a security device. A firewall, which will be part of any sane router's NAT implementation, is a security device. NAT is not a firewall, but is often part of one.

Any sane router also uses a firewall for IPv6. A correctly configured router will deny inbound traffic for both v4 and v6. You are not less secure on IPv6.

IPv4 requires a DHCP server. It requires assigning a range of addresses that's usually fairly small, and requires manual configuration as soon as you need more than 254 devices on a network. The range must never conflict with any VPN you use. And there's more. Compare to IPv6: Nothing. All of these just go away.

And concerning the NAT: That's just another word for firewall, which you still have in your router, which still needs to forward packages, and still can decide to block some of them.