Nomads are shepherds moving from one location to another according to a seasonal path. Digital nomads could behave in a similar fashion.
On the other hand, when I imagine the ideal nomad lifestyle, I think of Henry David Thoreau, his essay on walking and living in Walden, and how he traveled.
I can see myself in my 30s combining the two ideas.
I could buy a cheap plot of land in two different countries--say, Spain and Sweden--and share my time between them to take advantage of the weather.
I would learn bushcraft and make myself a cabin like the ones you can see on Youtube self-reliance channels.
If I were to stay at least three months in each location, I could also live off the land. For example, lentils are sown in spring and take three to four months to harvest. Two to three months for white kidney beans. Common vegetables, such as lettuce, green beans, onions, or tomatoes are even easier to grow: from one to two months to harvest.
Green transportation between the two countries would also be possible. The great thing about being a European is the ability to pass through the member countries of the Schengen area without needing a visa. You can use the European long-distance cycle routes (EuroVelo) to safely travel across countries while enjoying the scenery. The Sun Route is 7,050 km long and connects the far North of Sweden to the sunny South of Italy. You can complete it in 89 days if you bike 80km per day, but of course, you'd need less than that to go from the South of Sweden to the South of Spain (about 4,500 km, 56 days). You could also alternate between biking and taking the train to speed things up.
This is one idea among many to become more sustainable as a digital nomad.