Why is there not a non-typical UBI trial run by those who believe in UBI? It doesn't have to be tax funded and it doesn't have to pay out in a low purchasing power country.

For sure there is a 'living on one dollar a day' community that is willing to receive a UBI. That would be $400 per year. With a $4000 pledge per year, it takes 1000 people to finance a 10000 community. Add some technology transfer, and if UBI works, then the community should be able to finance its UBI by themselves after some years.