Is he actually doing that or is he doing what Casey Muratori's doing with Handmade Hero and taking almost a decade to implement a debug room for a generic top-down Zelda clone?

You can watch the streams and decide for yourself.

In a recent interview he mentioned they are aiming for a release later this year: https://youtu.be/jamU6SQBtxk?si=nMTKbJjZ20YFwmaC