How to sync Android and iOS photos? I currently have iPhone 5, iPad mini, MacBook Air and iMac.
I use the iOS and OS X Photos apps to store my photos and to share select photos with family. My photos are stored in iCloud for purposes of personal storage, and shared with spouse and parents via iCloud Photo Sharing.
I am desperate to move back to Android for my phone device (probably Nexus 5X) but feel the photos part is locking me in to the Apple ecosystem.

If I return to my Android heartland after too long away, What, if any, ways exist that would help me sync my Android phone photos with my other iOS/OS X devices - and vice versa? In other words, how can I get as close as possible to having a single, cross-platform photo library on both Android and iOS/OS X? When I take a photo on Android, it would also appear in my Apple photo library on both iOS and OS X devices (ie. in iCloud)? Likewise, if I took a photo with my iPad or added a photo to the Photos app in OS X, it would appear back on the phone.

I am investigating Google Photos on iOS and web. I fear family won't want to use this on their iOS devices for sharing. I love the auto photo identification but other aspects of it look weak.

Really struggling with ecosystem lock-in.
How can I ween myself off but only partially?
Maybe too late for this answer, but did you try IFTTT?

https://ifttt.com/connect/ios_photos/google_drive
https://ifttt.com/connect/android_photos/ios_photos