There is an IPv4 to IPv6 transition protocal called Lightweight 6over4 (RFC 7596). There is an open source implementation of of the "lwAFTR" function, which is basically the NAT concentrator. The client piece, called the "lwB4" can be implemented with built-in linux commands. Here is a link.
Lightweight 4over6 B4 Client in Linux Namespace
RFC 7084: “Basic Requirements for IPv6 Customer Edge Routers” states that CE routers SHOULD support IPv6 transition technologies like 6rd and DS-Lite. lw6o4 is an extension of DS-Lite and it would make sense to suport all three.
I also just learned about RFC 8585: Requirements for IPv6 Customer Edge Routers to Support IPv4-as-a-Service, published three months ago. it states,
Since it is impossible to know prior to sale which transition
mechanism a device will need over its lifetime, an IPv6 Transition CE
Router intended for the retail market MUST support all the IPv4aaS
transition mechanisms listed in this document.
Those transition mechanisms are DS-Lite, 464XLAT, lw4o6, MAP-E, and MAP-T.
GPL Licensed MAP-E/MAP-T CPE implementation- https://github.com/cernet/MAP
Bump. I asked about this during the Animal Farm webinar just now and I received no response.