A personal blog would likely qualify for that, however, many personal websites would not pass the test of "no connection to a professional or commercial activity" (from https://gdpr-info.eu/recitals/no-18/) - if you sell something on that site, or have ad revenue, or use it as advertisement for your professional consultations, then it's not purely household activity.

If you have a bootstrapped web startup project that you want to launch (e.g. collecting "pre-sales" signups from a minimum viable product), then it's definitely not purely personal or household activity even before you have registered a company.