If you use a single shared public ip then you’re using some amount of address translation
This is practically never the case with IPv6. Usually, each device gets its own public IP. This is how the IPv4 internet used to work in the old days (one IP = one device), and it solves so many problems. No need for NAT traversal since there's no NAT. No need for split horizon DNS since the same IP works both inside and outside your network.
There's still a firewall on the router, of course.
At least that’s how I understand ipv4 and I don’t think ipv6 is much different.
With IPv6, each network device can have multiple IPs. If you have an internal IP for whatever reason, it's in addition to your public IP, not instead of it.
IPs are often allocated using SLAAC (stateless address auto config). The router tells the client "I have a network you can use; its IP range is 2001:whatever/64, and the client auto-generates an IP in that range, either based on the MAC address (always the same) or random, depending on if privacy extensions are enabled - usually on for client systems and off for servers.