>>101129346She could have joined NOA with her current IP. The Gen 1 girls did. Likewise with Vshojo and some other agencies, so we can rule them out too.
She's very likely joining Holo EN, or maybe Phase as a non-Invader (i.e. she keeps the Nyana IP but streams under an IP owned by Fishman). Probably not joining a smaller agency, since she already is (was?) a fairly big indie in her own right.
Almost certainly not Niji EN; she's too big, too fluent in English, and too "not physically in Japan" to not have noticed the everything of the past year and a half.
Absolutely not Vallure, since she doesn't do R-18 NSFW content. Yes, all six Gen 1 girls are gonna be at her concert this weekend, but Stronny isn't gonna hire a girl without a porn-folio no matter how well they get along; Doki is more likely to get accepted than Nyana for this reason, and the full extent of Doki's porn-folio is that one time she played Hunie Pop and tripped at the finish line with the censorship.
If she's not joining Holo or Phase, then she's probably joining one of Brave's agencies. If she is joining Brave, then I hope she isn't joining Idol or Globie.