As things are, Flow does not 'read' the standard approval status of a SharePoint list. I do not want to turn the 'Approval status' into a choice field just to get the Flow working. Is there another way?
If you are using Microsoft Flow (not SharePoint 2007, 2010, or 2013 workflow) you need to do this:
- Remove any SharePoint Approval feature on the list or library and
- Remove any existing workflow subscription of any kind exists, i.e.: no 2007, 2010, or 2013 workflow exists for the list.
- If you started from a template that includes ‘Approval’ - start from scratch.
The approval disposition column you speak of is not accessible via Flow. You have to make a choice: old SP XML workflows or Flow (as of right now).
Flow has its own approval mechanisms built in - that do not rely on a list column because the technology uses the common data service across all (or at least most) O365 applications.
Therefore the very thing you Do Not want to do is what you must do if you require a column for Approval Status to be visible to end users And desire to use MS Flow.
Edit: I would instead use a calculated column that relies upon other column(s) to manifest this to the user, but I would not have the flow key off of it.