My biggest concern are sudden policy changes, like "as of the midnight last night..."
This is exactly what happened on June 1st at the Greek border with Bulgaria, where a score of Serbian tourists, many families with small children, lured by the prior Greek government announcement that the travel will start freely on that date, were stuck for a day or two.
If traveling from Belgrade to the States, I can not go via Schengen European states, even on transit flights.
There is a direct flight from Belgrade to NY, then I could take a local flight to Miami. Sounds good coming to the States. But going back the same way, via NY, might be a problem. At some point, NY instituted a quarantine for travelers from Florida. Whether it is still in force, and whether it applies to transit flights like mine, is something I do not want to be in the position to find out on the spot.
My only option currently is to fly via Turkish Airlines and Istanbul to Miami. Their airline food is excellent, they even have a chef on board. On the minus side, possible policy changes overnight.
In the meantime, I can only watch flights landing in Belgrade: