> The stuff on my network assigns itself ipv6 addresses based on their mac address? That's how you can do stateless ipv6?

Nit: per RFC8064[0], most modern, non-server devices do/should configure their addresses with "semantically opaque interface identifiers"[1] rather than using their MAC address/EUI64. That stable address gets used for inbound traffic, and then outbound traffic can use temporary/privacy addresses that are randomized and change over time.

Statelessness is accomplished simply by virtue of devices self-assigning addresses using SLAAC, rather than some centralized configuration thing like DHCPv6.

[0] https://datatracker.ietf.org/doc/rfc8064/ [1] https://datatracker.ietf.org/doc/rfc7217/