+1 from me as well.
As to the resources vs manufacturing discussion, I think it should be both. Trying to resume the whole thing while adding some of my own (underlined), you tell me if I get that right :
First kind is resource-based: Some resources at a certain place might be better in one way or another. How this happens needs to be thought out though: just a chance roll?
Second one is crafting-based: Someone might discover a better way to craft a certain object and teach it to their guild, needing to have apprentices uphold the tradition or write down the secrets to it. Apprentices with more need to uphold tradition and greater care for it should require less effort to become successors in the craft. When it comes to books about these craft secrets, they need to be stockpiled in their respective guilds, not a random library, making the guilds become owners of a trade secret.
Creation of a new notable product will need to have a large quantity of a high quality good, possibly by a skilled craftsdwarf. That quantity can be reduced depending on whether its creation is currently mandated by a noble, the higher their position, the lower. (Imagine that, useful nobles...)
Once the threshold exceeded, a new style is created and will have a name related to its' craftsdwarf, the settlement or its site government. Depending on the product the style came from, it can be applied onto different objects (i.e. Art Nouveau can be architecture, statues, paintings, not just one thing).
However, especially for food and intermediate goods, it can also have stricter requirements, like a special type of milk (you don't make parmesan with goat-milk), or even workshop requirements, like it must be made in a dolomite kitchen (as in, stone oven pizza, right?)
Traditions can be lost and the new notable product will be lost forever, causing a negative thought in dwarves that care about tradition and guildmembers. Also, if the recipe for a crafting-based notable product gets passed on from a site government to its civilization, the name might switch from its site government based name to a civilization one.
When it comes to the effects of a notable product, it can vary: In weapons it would select a token like damage, stick-chance, crit-chance etc. and give it a small boost.