I'm considering an architecture where my MS Flow Approval will access my Office Add-In site via the REST client action. It will pass the link to a file. The Add-In (which is also used by Office clients for other things) would then process business logic on the file and update the file contents and its SharePoint metadata.
I haven't noticed where this pattern was implemented. But, I'm new to Office Add-Ins and Office JS. It seems like it would work. Does anyone know an example that does this or if there's a reason why it wouldn't work?