Is it:

UIT is...
or
UIT are...
??

UIT are...

Excerpted from the Backstory:

"The UIT are happy to contribute their own technology to the effort, however, providing the Itani with many ingenious but often low-tech, solutions to problems."

but, isnt UIT a single nation, say like, the USA?

The UIT are a more loose knit band of 'states' and are not as single and indivisible as the USA.

The main reason is that each corporation acts on their own whether outside or inside the nation while the states of the USA acts as one under a single government outside of the country.

Maybe someone better informed about this subject of proper grammar can explain it.

UIT is the name given to a group of independent territories.

UIT are responsible for a number of innovations.

It depends on your usage.