That's why they were banned back when I took the tests. Have they loosened the restrictions on the n-spire?

The standard back in the early 2010s was still definitely TI-84 being about the most powerful calculator you could use for most tests that mattered. Those calculators are intentionally kept slow by TI because of these requirements.

My impression of the n-spire was that it had always been marketed much more towards professionals. The first one I saw in person was at an electrical engineering internship where my boss had just bought one.

No, they're still banned, but I got one early on when they were first released before they were consistently banned, and I realized shortly after that you could load some apps on there that basically allowed you to plug questions in and get the answer, since many problems are formulaic.