(a) you are processing data of data subjects who are in the union related to the offering of goods or services to such data subjects, or
(b) you are processing data of data subjects who are in the union related to monitoring of their behavior as far as their behavior takes place within the Union.
If you can avoid both of these, then I believe you can pretty much ignore GDPR.
If you have "no interest in doing business in Europe", it should be easy to avoid falling under (a). Recital 23 [2] discusses what it means to be "related to the offering of goods or services" to data subjects in the Union.
It means that you have to envisage offering services to such people. The mere accessibility of your website to EU people, or having an email or other contact details in the EU, is insufficient to show such intent. If you offer your website in EU languages that are not generally used in your non-EU country, accept EU currencies, mention your EU customers on your site, and things like that, will strongly suggest you are offering them goods and services.
What monitoring of their behavior means is discussed in Recital 24 [3]. It basically means tracking a person for profiling or analyzing or predicting their personal preferences, behaviors and attitudes.
Most sites selling things to end users probably don't need to do any such behavioral monitoring. If you do, just do a geoip check and exclude EU IPs. If you aren't trying to do business in Europe you probably want to do that anyway, because EU visitors are just noise in your data.
[1] https://gdpr-info.eu/art-3-gdpr/
