Request to implement PREF64 support to assist with IPv6 transition. This helps with client implementation of 464XLAT/CLAT as a migration to IPv6 only networks.

https://www.rfc-editor.org/rfc/rfc8781

radvd has implemented support in the 2.20rc1 release candidate
https://github.com/radvd-project/radvd/blob/master/CHANGES
https://github.com/radvd-project/radvd/pull/179

There is a current pull request with FRR: https://github.com/FRRouting/frr/pull/11224

Reference post on IPv6 mostly networks: https://labs.ripe.net/author/ondrej_caletka_1/deploying-ipv6-mostly-access-networks/