Open 0xr.space on a Meta Quest or an Android phone, press Open and choose the .vrm, then press View in your space, then Scale and 1:1 Size. The avatar stands in the room at the height it was made, with its MToon toon shading and outlines, and its spring bones move hair and clothes as you turn or carry it. VRM 0.x and 1.0 both open. The file is read on the device.
It is a viewer, not a VTuber app: there is no face or body tracking, expressions are not driven, and the avatar's licence and author block is not shown. Outlines set to screen space are not drawn; world-space outlines are.
Yes, and VRM 0.x. MToon materials and spring bones from both are drawn.
No. There is no tracking or pose control; the avatar stands in its rest pose, or plays an animation the file carries.
Not yet. Check the licence where you downloaded the avatar.
No. It is read on the device, and nothing is sent to a server unless you create a share link yourself.