Feels like the wrong approach. Why not just create a docking station for the iPad and a software docking view? Identical to Google's approach with the Pixel Tablet but Apple's superior will be more refined. It even uses the A18 SoC!
At $299 this feels like a very niche product with limited functionality.
$299 makes me think they want to sell something at-cost or at loss to get people onto services more. And it's intentionally gimped to not compete with any of their more expensive products.
They’d have to make iPadOS multiuser, which they’ve been avoiding for 16 years, despite constant requests from the user base.