In real-time rendering, a lot of innovation and state-of-the-art is published in non-peer-reviewed conference slides by companies, or blog posts by non-academic

In real-time rendering, a lot of innovation and state-of-the-art is published in non-peer-reviewed conference slides by companies, or blog posts by non-academic individuals. These should absolutely be cited if you as a researcher are convinced they are correct. There is no good reason not to.