There are over 500 distinct autonomous semi-sovereign cultures in the US, currently siloed in just as many reservations.

This is only counting the ones recognized by the Federal government, there are some only recognized by state governments, some with no land, some not recognized by any government.

There are plenty more in Canada too, and Mexico, under completely different and incompatible systems.

If you found the Najavo nation shockingly undeveloped, note that they are pretty much the most developed and organized of them all.

North America could be dotted with microstates just like the map of Europe shows, with more awareness of whats going on.

I dunno about that, the reservations around Tucson have housing with electricity and water. They’re not mansions, but pretty close to what other poor people lived in nearby. What he’s describing sounds exceptional from my POV.

When you get far from other people that becomes the norm. I know of regular people who live in Northern Minnesota without any utilities - they could get it, but they have to pay for the connection. Something like 10 miles to the nearest power pole, they could connect to, and the utility wants more than $10,000/mile (which isn't price gouging, if you look at the labor and materials this is their cost). That area is relatively populated compared to some western states.

Some people who live remotely arrange off-grid solutions, such as solar and wind power on site and water catchment systems, re Earthships et al.

That approach might be a better solution for the Navajo Nation and other Native peoples on reservations. There would still be financing challenges, but it's likely cheaper overall and more sustainable than running pipes and cables long distances out to remote locations.

While your conclusion is true, you shouldn't draw it based on real estate. There isn't much incentive to build, improve, or maintain a house on Trust Land (i.e. a reservation) when the occupant can't own it.

The wealthier tribes, such as those on the Washington Coast, have the vast majority of their members living off-reservation by choice because of exactly this issue.