Lots of countries have. I was on one of the last flights to transit through Taiwan. Here in the UK, the government have been talking about a program to get brits back from Australia because many of the places you have to stop and refuel are closed even to transiting passengers. https://www.aljazeera.com/news/2020/03/coronavirus-travel-re... https://www.gov.uk/foreign-travel-advice/australia/return-to...
There is/was a commercial non-stop from Perth to Heathrow, and with how many people they'd be flying, you could also use a half-filled 787.