We see that passenger aircraft have recently made cargo flights so that the supply chain does not decrease due to the Covid-19 crisis.
It is seen that the cargo boxes are loaded on the passenger seats by fastening them with a strap or rope.
https://twitter.com/AHoensbroech/status/1243095677485436928?s=09
Are there any regulatory restrictions (firefighting, smoke detection, aircraft weight&balance etc.) or guidance on carrying loads on the main deck of wide-body passenger aircrafts without removing the passenger seats (there will be no passengers on board)?