We just returned from Egypt. The wandertest results with QR code we got at MSP, were back in about 45 minutes (RT-PCR test but rapid results). Worked fine
We had a QR code. No one at airlines or immigration in Egypt read the code (though others we met did have agents at both scan their code).
We flew with Qatar over but our initial flight in US was AA. Qatar did check our tests before we boarded our flight in Chicago but a cursory glance. AA agent was more thorough reading through the requirements on the screen and checking what we provided.
Frankly I think they were just all grateful we had our paperwork gathered and in order. Sounded like they get a lot of people who are missing things or generally a mess

We had friends from Atlanta area who found a lab that would stamp the results (the alternative to a QR code). They said they had to drive a ways to find it though.