Download the model from the generator as a GLB, open 0xr.space on a Meta Quest or an Android phone, press Open and choose the file, then press View in your space. The model stands in the room with you. The file is read on the device and is not uploaded.
One thing to know first: a model generated from a prompt or a photo has no real-world size. Generators pick a scale of their own, so a mug can arrive as big as a sofa. The viewer shows the bounding box, and you scale the model by hand to the size you meant.
The generator never knew the real size. Scale it by hand; the size readout follows the model.
Yes. An imported model is kept in the browser's storage on that device, so it is still in your library next time, even if the generator later deletes it.
Create a share link. Anyone who opens it sees the model, on a phone, a computer or a headset. Share links expire after 30 days.
Not unless you create a share link. Opening and viewing it happen on the device.