A:AnswerJust a heads up, if you're going to be adding a GPU you will also need to change out the PSU as its only a minimal 180W one that comes with the PC. Even if you go with an older 3060 GPU, it'll require at least a 550W PSU.
A:AnswerThe pic I found of the internals shows it as an m.2 card ssd. I'm uncertain of the tech in it, as it could be NVME or SATA internally.
So it IS m.2 (and definitely not a 3.5 drive), just might not be NVME.