Clean meat could also have a huge impact on CO2 levels. According to Vinod Khosla (source):
about 30-50% of all land area is used for animal husbandry
clean meat and plant-based alternatives could allow us to take back most of it
restoring this land would solve the carbon emissions problem by carbon capture (~100 out of 110 of the Intergovernmental Panel on Climate Change’s scenarios for carbon reductions on the planet involve freeing millions of acres of land for reforestation)
In terms of plant-based alternatives, I think nutrition research could be high-impact and neglected. It seems like people are focused on trying to replicate the taste of meat, but when I experimented with veganism, I found myself wanting meat more the longer I’d gone without it, and experiencing it to be unusually satisfying if I hadn’t had it in a long while, which seems more compatible with a nutritional issue—the same pattern doesn’t seem to manifest for other foods I find tasty.
I’m imagining a study which feeds participants a vegan diet along with some randomly chosen nutritional supplements to see which are correlated with reduced desire to eat meat or something like that. Or maybe just better publicizing already known nutrition research / integrating it into plant based meat substitutes—for example, I just found this article which says iron from red meat is absorbed much more easily—I do think I was craving red meat specifically relative to other animal products. (Come to think of it, I was also experiencing more fatigue than normal, which seems compatible with mild anemia?)