The various books on photochemistry, such as The Darkroom Cookbook and The Film Developing Cookbook already serve this purpose for chemistry. There was a thread about this a few months ago, and most or all of the common chemicals that go into developers are used in other industries for other purposes. Some are commonly available to consumers (e.g., sodium carbonate, ascorbic acid). As a worst-case scenario, you'd need to track down an unusual supplier for components like phenidone or metol, which today we buy from photographic suppliers like Photographer's Formulary or Art Craft. Of course, if traditional photography were to decline to the point that all such places went out of business, I suspect there'd be very little market for such a book, even free on the Internet. The main thing to add to existing books would be formulas that use nothing but what might be called "supermarket chemistry" -- things that can be bought at supermarkets, drug stores, hardware stores, etc. This would be developers like Caffeinol and Parodinal. Tips on where to buy other ingredients, such as sodium thiosulfate, might also be useful.
Emulsion making is another matter, and I gather a much tougher one to tackle. I know that people like PE do coat their own papers today, so it is do-able. I've never looked into it in great detail, though.