That said, a lot more people would probably use complex constructs if they were not so expensive to set up because of the advice needed. I just do not think LLMs help.
Also LLMs are great for picking apart complex bureaucratic procedures, figuring out what next needs to be done, what the meaning is of some 10 page pile of crap the tax office dumped in your mail box, etc. Especially if you are not a native German speaker. You can ask your critical questions, get it to explain stuff you don't understand, etc. In the end, you are responsible for your actions. Limited liability in Germany isn't that limited. So, spending some time on figuring out whether you are doing it right is hard work. LLMs help.
But yeah, don't vibe run your private finances and sources of income.
Those shouldn't be prohibitively expensive; even small businesses in the US can typically afford one. Just go ask them.
Having an accountant is one of the hallmarks of a legitimate business.
If you're doing it on your own without a professional to watch out for you, and advise you, and take care of the details so you can do more important things, it isn't a company, it's a hobby.
That's probably the very last spot where you want to use an LLM, especially not in Germany. One single mistake can cost you a fortune, and you won't be able to spot the mistake because you're not an expert. LLMs could be used to prime you for conversations with an expert (but be prepared to be corrected on points of law and fact) but they are no substitute. Corporate law is a legal minefield, tread with utmost care.
The whole proposition is in a way bizarre: if you have this problem you almost certainly can afford proper guidance and if you need to resort to an LLM for that guidance you almost certainly don't need such complex constructs in the first place!