Philosophy, global priorities and animal welfare research. My current specific interests include: philosophy of mind, moral weights, person-affecting views, preference-based views and subjectivism, moral uncertainty, decision theory, deep uncertainty/cluelessness and backfire risks, s-risks, and indirect effects on wild animals.
I’ve also done economic modelling for some animal welfare issues.
My first impression is that these techniques are pretty obscure and technical, and charities would not think to use them or know how to by default. In fact, sharing them here might make it more likely that charities use them (an infohazard).
EDIT: But maybe if motivated and strategic enough, they would find them through online search.