I have a web application set up, and I am using the configuration utility to set up an instance.
From what I understand, using the OGC API enables only one output, therefore I have to choose if I want to return the pixel value or the visualization (while using eval script).
I thought a workaround could be setting up two instances and then using one for the pixel value and the other for the visualization. Has anyone tried this? Or have different suggestions?
your understanding of the limitation of only returning 1 output when using OGC API is correct.
You don’t need a whole separate instance. A separate layer in the existing instance is sufficient - since a request to get the data contains an id of an instance as well as an id for a layer in that instance.
Having multiple layers for different purposes (e.g. for visualization on the map and for displaying raw pixel values) is a usual and valid solution.