Would a good way to test that be the new "Video" tab in the Speed Test app? And see what the highest video it says you can stream while on the network?
I've been seeing them "test" SA 5G here on N71 here lately. It comes and goes.
I'm on a Sprint Galaxy S21, now with a T-Mobile SIM. In the Cleveland, OH area.
Sprint S21 here, with T-Mobile SIM card installed last week. Since the SIM install, I've been seen NSA 5G. Now today, I saw SA 5G pop up. Speed test was slower than NSA, but it was nice to see SA.
We went to the T-Mobile store to have them install T-Mobile SIM cards in our phones. They had issues getting them to work with both our phones (wife has in iPhone 11). But they finally got it working.
No noticeable difference in service.