Open 0xr.space, press Open and choose the .blend file. Its mesh objects are read in the browser, with each material's base colour and the textures packed into the file, and shown as a 3D model you can turn, cut through and place in the room on a Quest or an ARCore phone. Files from very old Blender versions up to Blender 5 open, compressed or not.
It is a viewer for what is in the file, not Blender: modifiers, armatures, curves and anything that is not a mesh object are left out, and node materials come through as their base colour or base texture. For a faithful result, apply modifiers and pack textures before saving, or export a GLB.
Only mesh objects are read. Curves, text, metaballs and objects made by modifiers or geometry nodes are not, so convert them to mesh in Blender to see them.
Materials come through as a base colour and base texture, not the full node tree. For exact materials export a GLB from Blender, which this also opens.
Yes, along with older versions, compressed or not.
Yes. A .blend1 is Blender's copy of the file before its last save, and it opens like the .blend.
No. It is read on the device, and nothing is sent to a server unless you create a share link yourself.