Bolt 12 anonymised messaging will be a dumpster fire of spam, a straight up DoS vector, without being very very very carefully thought out. I don't think it will be implemented and will ultimately be moved outside of the purview of LN because it is simply too big to fit into a single Bolt.

I'm working on a project to build precisely an anonymisation relay network targeted at providing client side anonymity to user propagating transactions on Bitcoin or running privacy protected Lightning channels. It's purposely being constrained to that scope, as the "exit node" being LN and BTC nodes, to initially focus the implementation and shorten time to market, and reduce the feature set size to start with.

Ultimately it is intended that it will become the de facto transport for all Bitcoin and Lightning Network traffic, and grow the anonymity set with every kind of network service imaginable, and later implementing rendezvous routing to enable hidden services.

It's just me, l0k1(8) working on it for now. Participating in maker.bolt.fun Legends of Lightning to hopefully win a little extra funding but I have a sponsor who is keeping me from needing to chase any other thing. I am trying to keep my focus on the code but nobody else is doing the marketing either so I have to deal with that too.