Open 0xr.space on the computer, press Open and choose the model, then press Send to your headset. A QR code appears. On the Quest, open 0xr.space or the free Model Explorer app, press Scan and point the headset at the screen: the model opens there, ready to place in the room.
To make that link, your model is uploaded and kept for 30 days, after which the link stops working. A model from the site's own gallery is not uploaded; its link is permanent. If you would rather nothing leaves your machines, copy the file over a cloud drive or a USB cable instead and open it on the headset.
Only when you make a link. Send to your headset uploads the converted model so the other device can fetch it, and the link expires 30 days later. Opening a file uploads nothing.
Up to 512 MB in all, 350 MB for any one file. Over that, nothing is uploaded and the dialog says so; copy the file by cloud drive or USB instead.
Not yet. Splats and point clouds stay on the device they were opened on, so copy the file itself to the headset.
No. There is nothing to sign into to make the link. A free account, opened with a code sent to your email, lets you list and delete your links from any device. Making links is not offered in every country.