>>105862876
Yes. In fact, the Phase Invader Clio was waiting in the basement for ~2 years before she was finally able to debut, all the while she was streaming as an indie. All "invader"-type debuts are the same way - maybe not having to wait 2 years, but the vtubers continuing to stream as indies while actually being signed to a corpo and working towards a debut.
If you want a non-invader example, let's look at Raora/Yuniiho. According to Gigi, all the members of Justice were selected in November 2023, but Yuniiho (and Biscotti/Gigi for that matter) didn't graduate from their previous personas until March 2024. So during that in between time they were "pretending" to be indie/V4M, while actually being signed to Hololive.
The only difference with Mint, is that she never got to debut because Vshojo kept on pushing it back.