Not true. It very much was an official announcement. It was announced by the Secretary of Homeland Security at a House Committee Meeting.
It was triggered by a question that seemed to be set up as a lead-in, but he read from a prepared statement. Politico had published that the announcement would be made - and they published that prior to the meeting. So yeah, it wasn't a spontaneous answer to a question, so let's dispel that bit of misinformation by you.
The announcement of the Board was handled poorly, by Mayorkas's own admission.
And when he was given the chance to clarify things yesterday in a planned spot on CNN, he still didn't provide a whole lot of detail on what the Board will actually do. On the positive side he did state clearly that "American citizens will not be monitored." He also said that the Board will not have operational authority. But when pressed twice about what they'd actually do, he resorted to word more salad - "they will gather together best practices."