thanks for your answer and yes I've read that article.
As far as I get it, if I want to have a GDPR compliant website within the personal plan I can't use google analytics or any other third party services, that leave cookies. The banner solution that's offered by Squarespace takes care of cookies placed by Squarespace, so I can leave Squarespace analytics active.
If anyone knows of some way to run Squarespace personal plan websites with Google analytics and GDPR compiiance, I'd be really grateful. I can't quite believe, that this really isn't possible, if that should be the case, it's a major deal breaker!