I mean is this really one word though, or a bunch of words just spelled with no spacing?
It really is one "new" word consisting of a bunch of words spelled without spaces. It is a compound, where every word adds additinal information to the last component. An easier example is sth like "Altbauwohnung" which would be an apartment (Wohnung) in an old (alt) building (Bau) where "Altbau" is also a compound. This way of compunding enables you to build new words everyone can understand the first time they encounter them, but also to build those stupidly long words.
What if I said in English, you can "compound" words with adjectives so for example if you have a book, you can add red and say redbook, and you can keep going and do stuff like uselessoldreddirtyneverusedbook. You can even add possessives which have their own adjectives, like if the book was owned by a redbearded german army vet you'd say
The redbeardedgermanarmyvet'suselessoldreddirtyneverusedbook
It’s one word, like watchmaker or bookkeeper are in English.
What is your definition of “word”? This is not at all a simple question in linguistics. By the way, it can’t just be “written without spaces”, as languages with no writing system at all, and languages whose writing system has no spaces (like Chinese), still have various concepts of “word”.
It is one word in German. It has one article, Germans talk about it as about a single word and treat it as a single word for grammar purposes. You can use it as a single noun in any sentence.
But it also odd example for this, because it is long as hell anyway already and additional spacing that English equivalent would require is just opportunity to wrap. It is just harder to read, but English equivalent would be easier to layout.