Open 0xr.space, press Open and choose the .amf, plain XML or zipped. Its unit is applied, millimetres when it names none, so the part opens at its real size, turned from the build plate's Z up to stand upright, and every instance is drawn where it was placed. Info shows the size, the volume and whether the mesh is watertight.
Colour is limited: the first material's colour is used for the whole model, so a multi-material AMF shows one colour, and per-vertex colours, textures and curved triangles are not read. Print settings and supports are not shown. This is the model, not a slice. It is read on the device and nothing is uploaded.
Yes. An AMF says its unit, millimetres when it says nothing, and it is applied when the file is read.
Yes. Several slicers write a ZIP with the .amf extension; the model inside it is read.
Only the first material's colour is used, for the whole model. Colours on the volumes or vertices are not read.
Yes. On Home, open the three-dot menu on its card and press Download STL, in millimetres and Z up. Downloading needs an account.
No. It is read on the device, and nothing is sent to a server unless you create a share link yourself.