About Interlude.
From a technical point of view, Interlude makes more than sense. And why? DPC wrote it himself.
"I will release the interlude before episode 9. This gives you some more Being a DIK content faster, and it also gives a perfect opportunity to make sure that the save transfers from Season 2 to Season 3 works for all of your games."
Zoey not being integrated into the game until later was probably planned from the beginning, and if DPC hadn't needed a memory transfer (due to memory consumption), the Zoey flashback would likely have been integrated into EP9. But it needed the memory transfer from season 2 to season 3. Now imagine if the Interlude was not available as a memory transfer platform and all of EP9 was the interface for the memory transfer. Then players who have multiple runs with different paths would have to play through all the runs with EP9 to have clean saves for EP10. Interlude can simply be skipped after one run and the player will have a clean save for EP9 afterwards. For this reason alone, Interlude has a reason to exist.
Also, DPC needed to make saves compatible for the Patreon, Steam, and Gog versions of Season 3, and they needed to do that already for EP9, not just for EP10.