Yes, QUANGO is a Scrabble word!

Letter values in Scrabble US: Q 10, U 1, A 1, N 1, G 2, O 1.

Is it a valid word?

QUANGO is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

a quasi nongovernmental organization; an organization that is financed by the government yet acts independently of the government

Also: quasi-ngo.