Hi,
switchport is a Layer 2 configuration.
There are two types of switchports: trunk or access.
port that configured with switchport (access or trunk) can pass both IPv6 and IPv4.
A Layer 2 port can transmit / receive both IPv4 and IPv6
To see where IPv6 device is connected:
show ipv6 neighbor binding
show ipv6 nd
show ipv6 neighbors