Blaming GDPR for this is a bit like blaming a lead mine for getting shot. Yes, it's involved but it's not the reason. It only seems to be certain large US websites that carte-blanch refuse to serve EU visitors over GDPR, mostly those with large, tendril-filled advertising networks that have no "easy opt-out". Some sites (healthcare ones that tended to be SEO'd to the max when I searched for drug names as well as more mainstream ones like, iirc, the Washington Post) carte-blanch refuse to let you browse them without accepting unnecessary cookies; this is a direct breach of the legislation and yet they still want your traffic.
If someone won't sell you something because of GDPR -- legislation that protects your privacy, and in particular considers medical information as especially sensitive -- then you perhaps have to think rather carefully about if you wish to do business with them.
(For what it's worth, from a Danish IP, the site listed in the github repo works perfectly on my home network which admittedly contains a pihole-provided dns-level adblocking. It blocks tor and I don't have an easy way of testing it otherwise).