...that's it.
This is an alpine box, so it's fairly small.
Something along the lines of:
docker run --rm \
--net=host --cap-add=NET_RAW \
-v /etc/radvd/%i.conf:/etc/radvd.conf:ro \
quay.io/rsrchboy/radvd -d 2 -m stderr
...substituting rsrchboy/radvd
if you're in a hub mood :)
man 5 radvd.conf