This looks interesting. It allows you to save your games across platforms and it’s free if you release your game on xbox. Anyone want to make a defold extension for this? 
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This guide will help you make your first PlayFab API call using Defold.
Note that:
“This is a community supported SDK.
For new and existing users, you can use the current version as it is. The team at Microsoft would no longer be providing official support for those using this SDK. You can continue to get community support and updates at PlayFab forums.”
Wow. I had no idea this was already there. Thank you. I wonder if there will need to be updates to do the cross platform saves.
If you want something that is updated and maintained then look at Nakama instead.