Another thing around testing requirement before you're given a boarding pass - how would this work in inter-connected tickets that start in small towns. Lets say I have a flight (single-ticket) GST-JNU-SEA-DXB, and the Emirates flight SEA-DXB would require a test taken before issuing a boarding pass. Or DRO-IAH-SCL, where entry into Chile requires a negative test and negative test kits don't exist in the small durango airport only at IAH.

How exactly will even the boarding pass be issued when obviously a small outstation like GST or DRO will never have test kits needed for international flights. Typically all documents and requirements are checked at the first point of departure. Will this mean there will now be a need to run tests during short connections? Will minimum connection times be increased to 5-6 hours to account for this?

This is just one small example - there can be many more similar ones.

Testing people at the airport (besides walk-through temperature scanners) is simply not feasible at scale.