If you're looking for some GuP goods. Megami MAGAZINE December 2023 issue is a great GuP collection.
It has article about Das Finale 4 which include highlight from DF4 (pictures & comment - a spoiler, of course) GuP's 3D director and military supervisory staff talks, and the interview with Azusa and Youko's voice actresses.
Sample pages (DF4 spoiler)
https://imgur.com/1eJqDSq