One interesting different is that in most of the US you're usually in the clear if whatever you work on isn't related to your employer's business (although that can be a bit nebulous). However my understanding is that in Germany, even if your side project isn't related to your employer's business you're still required to give them first dibs at licensing any IP you create.

It is purely a contractual question. So if your contract states rules like this - you are right. But without written agreement in the contract your employer has no rights to your work done during your free time.

At least, as far as I understand after reading up on the regulations and the text of the respective laws.

I think my employer has something similar, but it ties in with the no-compete clause. That said, there's more of a gentlemen's agreement in place, and if you verbally mention it to the boss it's fine in most cases.

But having a job in industry X and a side gig / personal project also in industry X is dangerous.

I was under the impression that corporate employed inventors in Germany actually have a limited interest in their inventions that follows them between employers. Could be it’s changed, or my source is simply mistaken, since my knowledge is back from when Kodak AG was still a thing.

I've been guilty once or twice of forming a strong (usually self-righteous) opinion only to have it collapse before I get a chance to enjoy smugly lecturing the Internet. This is interesting. Thanks for posting anyway.