People tend to forget that Superman was holding his own with Zod... who had a lot more experience in battles. Thanos was getting staggered and hurt by explosives, Spider-Man, Captain America and Iron Man. Sorry but he's got nothing on Superman. He was cut by Iron Man... one punch from Superman would hurt him a lot more.
So her speed is travel speed, not combat speed; so I'm not sure how important it is.
And this is probably lowballing her a little bit; but since we don't really have more information it's the best I could do:
Friday says something is entering the atmosphere, which is 100 km from earth. It's maybe 10 seconds later when Carol arrives to earth. That's 10 seconds to go 100km. 100km in 10 seconds is 360 000 km/h. That's roughly 291.5 times the speed of sound.
Thanos' ship had been firing on her for 3 to 4 seconds prior to the Avengers asking what it was firing on when friday said something was entering the atmosphere.
Lets also remember that in Avengers 1 with vastly lower capable armor Jarvis eas able tondetect exactly what was outside the atmosphere coming in (indicating that Stark's earlier armor could sense well beyond the range in question.
The fact that Friday couldnt say what it was indicates it was vastly more than 100km. And she travelled even farther. She then reacted to all their attacks and salvos while at that speed (which is a combat speed feat not a travel sleed one).
Travel speed isn't combat speed. Travel speed has 0 advantage in this fight.