An interim has weeks, not quarters, to become useful. What you hand over on day one decides how much of that time goes into the work rather than into archaeology.
The numbers as the team actually uses them, not as the board sees them. The three decisions currently stuck. An honest account of who is leaving. The contracts that expire this year. And the thing nobody says out loud in meetings.
That last one matters most and is the one most handovers omit.