arc-vr VS VirtualMotionCapture

Github Repo

Virtual Motion Capture is another free option which allows you to add your VRM model into the software and use your VR headset's trackers to move your model (Granted I prefered Liv's movements more). If you pay for their Japanese Paitron-like thing (300 yen, around $2.5 dollars) you'll gain access to the ability to send that tracking data over to vSeeface which would be preferable as neither of these two softwares provide bone physics or other customization that vseeface allows.

I suspect she is most likely uses something like Vseeface or VirtualMotionCapture (which integrates into VSeeface) and then loads that into her character app. Unfortunately the exact app might not be known. The character modeller for the new 3d model is jjinomu, who works in VRM format. Which means it's possible it could be anything from Unity to Luppet, VRoid Studio and some others. (Odds are though it's an off the shelf solution, as few vtubers are doing Unity/Unreal specific work.)