> A huge part of GHG emissions is due to deforesting and cattle

Deforestation is clearly an issue, but I seem to recall reading about a diet with some/more/lots of seaweed essentially solved the methane issue of cattle?

If the deforestation is to have space for cows the answer is obvious: cow/fish hybrids. Or cows with scuba masks? No need to collect the seaweed, no need to destroy the forest.

You’ll need bigger fishing nets though.