It would be nice if the GDPR had a piece about “if a company refuses sales, even if they accidentally happen, the company isn’t liable” and/or “blocking EU IPs or redirecting to a no sale page is sufficient to avoid compliance”.
https://gdpr-info.eu/recitals/no-23/
> In order to determine whether such a controller or processor is offering goods or services to data subjects who are in the Union, it should be ascertained whether it is apparent that the controller or processor envisages offering services to data subjects in one or more Member States in the Union. 3Whereas the mere accessibility of the controller’s, processor’s or an intermediary’s website in the Union, of an email address or of other contact details, or the use of a language generally used in the third country where the controller is established, is insufficient to ascertain such intention, factors such as the use of a language or a currency generally used in one or more Member States with the possibility of ordering goods and services in that other language, or the mentioning of customers or users who are in the Union, may make it apparent that the controller envisages offering goods or services to data subjects in the Union.
By blocking EU IPs the service is very clearly, unambiguously, not targetting EU residents.
If you block EU IPs but your business is targeting Europeans who are on holiday - well, you probably still don't need to comply with GDPR because you've demonstrated attempts to actively avoid European residents.
The test in GDPR is not "does any European ever use the service?" but "are you targeting them?"