Consider researching Lelantus. Specifically Lelantus 1 instead of 2.
Beam’s Valdo already has: https://github.com/BeamMW/beam/wiki/Lelantus-MW
In Grin, we aren’t as willing to sacrifice mimblewimble’s scalability benefits for the additional privacy, but perhaps we could have a much smaller anonymity set of, say, 15. Not nearly as good as 2^14, but it’s still double the anonymity set of Monero’s ring signatures while still allowing us to prune the whole set once all 15 outputs are spent. It’s something that I’m looking into.
Maybe not anonymity, but activity, or am I not understanding something?