What are my options for displaying/simulating gauges outside the sim?

I use Air Manager with a knobster and love it.

Right now I only fly GA with steam gauges but also have a panel ready to go for the 172 with the Garmin 530/430 package.

When you get into the panel style you would be popping out the panels in the sim and moving them where you need them on another monitor for Air Manager to go overtop.

There is an extensive thread here

Which goes over all of this and a group here on the forum or creating great content and making it available.

Again this is all in Air Manager.