>4. Android QuickShare works!

Does that require being logged into a Google account? How to ensure Google knows nothing about your shares?

I have Graphene w/ Google Play Services (required for my job) and would love a easy way to share files/info with various devices (incl. iOS/macOS which I remember should work with QuickShare in the future) but will avoid a service that shares data with Google.

Unfortunately yes, and I am signed into my Google account for it.

That's a hard pass.