Kirk McElhearn has an excellent deconstruction of Apple’s new photographic format, ProRAW, which turns out to be mostly overzealous marketing lingo.
More, McElhearn comprehensively unpacks what RAW is, how it works, and how ProRAW differs from the more traditional RAW formats used in modern DLSRs and mirrorless cameras.
One of the key elements of raw files is that they are not demosaiced. Demoisaicing is when an algorithm interprets the colors of the various pixels according to how light is recorded after traversing color filters, applies white balance settings, and more. This is complex, and this article from the developers of the Halide camera app explains the process.