There's an rule in the EU that says you can't feed the insects pork and then let those insects go on to be fed to pigs (same for beef and chicken). This is intended to prevent the transmission of diseases like Transmissible Spongiform Encephalopathies (like "mad cow disease"). As I understand it, this rule isn't because we have shown it's dangerous to do the pig -> insect -> pig chain but rather because we haven't shown that it's safe. Arnold van Huis and his team at Wageningen University are putting quite some energy researching the safety and lobbying the EU to change the rules based on the findings. At one of the talks those folks they said it's basically a black box of trying to get what kind of science the regulators will consider acceptable.

As you might guess, making sure the food waste you feed the insects doesn't have _any_ animal proteins in it is quite logistically challenging and so afaik nobody is doing that at a large scale.

I did quite a bit of research into the history of insects in the food system, especially in the Netherlands. While I was rooting for Ynsect and other big players to figure something good out I believe that it's a problem much better suited to a smaller scale (perhaps on the city level). Basically, have the food waste from various stores brought to a facility to be fed to insects and then let those insects be turned into whatever (pet food, fish food, trendy protein bars).