I won't to use domain names, maybe there is some way to run few IPv6 on the same Yggdrasil instance?
http://[222:a8e4:50cd:55c:788e:b0a5:4e2f:a92c]/yggdrasil:several_services_on_machine
You can add static IPv6 addresses on 300::/8 range on you network/interfaces, then you have the addresses.
Now you use docker containers to run the many sites, for each container, in docker run you can specify bind address:
docker run -p [ipv6]:80:80 ... so the container will expose port 80 for specific ipv6 address, you can use as many as you want. To avoid port conflict, ensure that there is no application on port 80 of host machine