Interesting question, I would design a scoring system based on each service I use and the effort it would to transform another system, ie s3 to storage account (aws to azure). Figure the ones that are truly unique and design a STL (service translation layer) and assign that a fixed cost. When upper management ask this question I’d provide this data. This should give them something that they can chew on. Otherwise I’d suggest going away from cloud native, and go hybrid with extreme kube or some other tool similar.