NWAC is a valid educational board as it is recognized by AIU(Association of Indian Universities). Therefore all colleges, either private college or government college, both will accept the education certificate issued by the NWAC Board. An educational certificate from this board is applicable to apply for any college or university in India or Abroad.

You can check out the Government approvals for NWAC board from the official website of NWAC board i.e.

https://www.seriindia.org/govt-approval.php

yes it is valid board. All private as well as government will accept the NWAC marksheet.