When I log in via the built in “Terminal” or via ssh to hassio, I get the system information including the current public IPv6 address of my installation:
Welcome to the Home Assistant command line.
IPv4 addresses for end0: 192.168.3.96/24
IPv6 addresses for end0: 2a02:xxxx:xxxx:xxxx:2c10:xxxx:xxxx:c1b9/64, fe80::a681:ba90:1676:a8cb/64
Of course, the IPv6 prefix changes from time to time on most private subscriber lines.
I wonder if it is possible to access this IPv6 address information from the shell? Is it stored in some variable perhaps?
Then I could easily create a command line based Dyn DNS update script.
BTW: Access from the outside via this address to my HA works perfectly.