"I'm surprised by how confident I did feel in the car, seeing as though it is an animal to drive those things. I think it's going to take a lot to maximise the car. These sorts of things don't come overnight. You can't just jump into an animal like that and maximise it.
"If my plans come to fruition it's going to be a progressive learning curve."
If Armstrong is able to negotiate his way into an IndyCar seat next season, he would be the third Kiwi to line up on the grid, alongside six-time series champion Scott Dixon and three-time race winner Scott McLaughlin.
However, he wasn't getting too far ahead of himself as discussions and opportunities remain fluid.
"I'm just sort of managing myself which is a bit of a new thing. I'm just taking it day by day. I think the teams over in America appreciate speaking to the driver directly, so I'm just seeing what we can get done.
"Hopefully I can do it – I'm managing myself so it'll be down to me. Let's see how it goes."
While his next steps are still up in the air, Armstrong will soon turn his attention to the final F2 event of the season. The circuit comes to a close in Abu Dhabi in mid-November, following a two-month hiatus.
With three race wins and seven top-five finishes this season, Armstrong goes into the final event sitting 12th on the standings with 91 points, but a good race weekend could see him move inside the top 10 to finish the year.