eq keyword should be used for Salesforce GraphQL API Equal To Filter.

For Salesforce GraphQL API connection setup from PostMan, please use the following

Connect Salesforce GraphQL API from Postman

In the following example, Accounts with Industry value equal to Technology are fetched.

Example:

query accounts {
  uiapi {
    query {
      Account( where: { 
        Industry: { eq: "Technology" }
      } ) {
        edges {
          node {
            Id
            Name {
              value
            }
            AccountNumber {
              value
            }
          }
        }
      }
    }
  }
}