Sync exchange with local calendar WITHOUT granting permissions to gmail or Samsung

It’s pretty simple, what I want, I think:

  • 1 local/offline-only calendar on the phone (default Samsung app)
  • 1 on-line exchange calendar (automatically synced)
  • ability to show one or the other or both at the same time in the same view
  • notifications coming from both calendars, as if they’re both local

I do NOT want:

  • to associate a google account with the phone
  • the gmail app to be in any way involved
  • to accept Samsung’s request to hold my personal information for 5 years on their servers
  • any kind of sync involving e-mail, contacts etc etc.

It amazes me that this seems nearly impossible to do. Is it/how?