>>67637598There's no way that's the case. Konami has very good relations with Nijisanji. Konami wouldn't go to Pomu directly for a song offer - they know full-well that things like that go through Nijisanji management.
It's much much more likely that it was a collab with an idol group. A couple months prior, Pomu released a song cover from her favorite idol group "Niji no Conquistador" (unrelated to Nijisanji). Multiple idols in the group noticed her cover, commented on it, and they became mutuals on Twitter. What probably happened with that they/their manager reached out to Pomu via DM for a collab (because they didn't know things had to go through Nijisanji management), Pomu brought it to management, but they shot it down because Nijisanji management is incompetent/lazy/malicious like that. It would have been a once-in-a-lifetime opportunity for her, and management declining it broke her heart because NijiJP has done idol group collabs before.