There were a few people that did this with Facebook years ago in Germany (GDPR is merely the EU-level legislature, some parts of it have existed in member state

There were a few people that did this with Facebook years ago in Germany (GDPR is merely the EU-level legislature, some parts of it have existed in member state law for a while). The result basically was that you got a DVD with a lot of PDFs on it, if I remember correctly. Including all things you once uploaded and later deleted, which were apparently kept.