Quick info: Part 2 was released back in January 2020: https://www.melonbooks.co.jp/detail/detail.php?product_id=624290. Unfortunately, I couldn't secure a copy of it at the time. Part 3 is still on the works: https://twitter.com/ogawa963/status/1325811789473357825. After a long hiatus, the artist miraculously came back a few days ago. Apparently, she will try to participate on Bokura no Love Live! 37.