A router (discounting unnumbered and ARP/NDP proxying) will have at least 2 IP addresses, otherwise how can it route packets between two different networks? It

A router (discounting unnumbered and ARP/NDP proxying) will have at least 2 IP addresses, otherwise how can it route packets between two different networks? It needs one IP for itself on each network. For IPv4, you will be given <some random IP> on the WAN side and typically you assign 192.168.x.x (or other RFC1918 addresses) to your devices on the LAN side. For IPv6, you will be given two random IP blocks with similar usage as the IPv4 ones, except that the LAN side is now publicly routable.