I was doing some tracing of Ina's career pre-Hololive earlier. I've no solid evidence that she's Nagu, but here's the links to her
Twitter and
Pixiv. If she's Nagu, then she's done pro-level illustrations.
EDIT: The main reason I might doubt that she's Nagu is how much of the stuff is in Japanese. It isn't that difficult, though, to translate and easily copy-pasted from DeepL or some other machine translation. Either way, though, your guess is as good as mine. If Ina can speak Japanese beyond basic stuff, she's kept a lid on it.