I’d say your client has to open their mind a bit. I’m not sure using multiple vendors to build the best data stack leads to unnecessary data exposure, but I can’t understand the skepticism. If that’s the case, you probably are best going with AWS, MSFT or Googles cloud offering and their data tools. Most of the big cloud providers have many services you can use to build your data stack, you just might not be getting the best of any world.