I'm American. re: COVID restrictions, can I fly through Portugal on my way to the Czech Republic in September? [closed]

I am a second year masters student who will be traveling to the Czech Republic in mid-September in order to continue my studies. All flights have layovers somewhere, and the cheapest/fastest flight I can find has a layover in Portugal. I will have a valid study visa for the Czech Republic, and will be required to have a negative COVID-19 test prior to entering the Czech Republic, and to show this before entering the country.

I have visited the websites of the Portugese Embassy in the U.S., the U.S. Department of State, and the U.S. Embassy in Portugal to see if there is specific guidance for traveling into Portugal in order to continue on to a third destination, but cannot find information on whether it is possible to simply travel through the country. The websites say that only "essential" travel is permitted, which includes traveling for the purpose of studies (though I won't be studying in Portugal), and that I must have a negative COVID test in order to enter the country.

I will have a COVID test and will travel with my results (as long as they're negative of course! Otherwise will not travel), so I am hoping that it will be fine to travel through, as I will not leave the airport. But in these uncertain times, I want to be absolutely certain that I will be allowed to a) board the flight, and b) enter the airport to take my connecting flight, before I book. Any insider knowledge on how such cases are handled in Portugal, or recommendations on who to contact to have this question answered?