That's correct. However, I've tried to use prune now, not sure if I am using it correctly, but that's why I do:

I build my packages regularly (not pruned), then I prune with scope "backend". Apparently the pruned directory contains node_modules with empty packages, not sure what reason is for that; I just ignored it. In the resulting directory I then run `pnpm install --prod`. Only the regular dependencies will be installed. I think this is enough for my usecase. I am not sure if prune is supposed to be used for this approach though.