Although this judgement was in Germany, I don’t see a reason that it would not apply to any other EU state, and I haven’t found any case law that says that an I

Although this judgement was in Germany, I don’t see a reason that it would not apply to any other EU state, and I haven’t found any case law that says that an IP address in isolation is not personal data. Anyway, there’s no requirement for any piece of data to be independently identifying in order for it to come under the scope of personal data per GDPR. A piece of information is personal data if it can be linked to an individual. This applies whether the linking can be done in isolation or only with other pieces of information, and whether the link is explicit or inferred, direct or indirect, and whether the controller/processor has immediate access to the other pieces of data or not. Even if you rely on legitimate interest as a basis for processing personal data (and you might do, depending on your actual interests), you still have to do your paperwork, complete the PIAs and balancing tests.