Which country's laws apply and what remedies you can get if they were violated is far more complicated than geolocation of data.

But very broadly speaking you would need to sue in an EU court to enforce EU law. And you could sue a US company in specific EU country's court if the company had more than some minimum level of connection to the that country. The country the data is hosted in isn't key, though it can be evidence of connection to that country.

Where the data is stored does not matter much. Laws deal with people and companies, so it matters where you live or where your company operates. So if you live in the US you don't have to worry about EU laws unless you do buisness in EU.