Two simple questions reveal how much land we could save by eating plants. Almost everyone guesses wrong
(veganhorizon.substack.com)
I mean, I hope you understand that vegans will not be experts in non-vegan solutions. I'm certainly not an expert.
But generally speaking: The only thing that produces calories on this planet are plants. Everything else is always just reusing those calories and therefore using up some of those calories to sustain its own life.
Yes, in principle there can be situations where introducing a middleman can make more calories available to us. Animals grazing on land where farming isn't viable is the classic example.
Having insects eat plant waste could be viable, although turning plant waste into compost as an alternative to fertilizer is also already quite useful.
But then you run into the other problem, which is that the scalability of plants is hard to beat. For the most part, you throw seeds onto barren land and the magic happens. You don't need VATs, you don't need personnel most of the time, you don't need electricity.
I could see certain processes being useful for certain niche situations, but so long as we can just sidestep that situation by growing plants in the next town over and transporting the food to where it's needed, I don't think, it's worth the investment.