With my recent purchase of a Retroid Flip I've been playing a lot more games on handheld, which is awesome, but I don't want to always play on handheld. Sometimes it's nice to still play on the big screen. So you run into a bit of a problem: running the games on two separate devices means two different save files, and you can't just pick up where you left off. There's an elegant, pretty easy solution to this problem. Google Drive, and a free Android app called Autosync. Autosync does what it sounds like - it automatically syncs between two folders using Google Drive. Setup is simple:

1. On your computer, make sure you have the Google Drive for Desktop application installed. This will map your Google account's Drive to the G: drive on your computer.
2. Inside the G: drive, create a new folder named "SyncBetweenDevices". (You can name this anything you want, but it's give it a descriptive name).
3. Open up Retroarch and navigate to Settings -> Saving. Make sure the following are turned OFF.
   1. Sort Saves into Folders by Core Name
   2. Sort Saves into Folders by Content Directory
4. Now go to Settings -> Directory, and scroll down to Save Files. Change the path to the SyncBetweenDevices folder you just created.
5. Make sure to save your RetroArch configuration file.

On your remote device (phone, android handheld, whatever), follow these steps:

1. Create a new folder on your device called GameSaves.
2. Download and install Autosync and open it up.
3. Give the app file permission and connect to Google Drive
4. Set the Local Folder as the GameSaves folder you created.
5. Set the Remote Folder as the folder in Google Drive you created earlier.
6. Open Retroarch and make the same changes to Saving, and set your Directory -> Save Files path to the GameSaves folder.

Now when you play games on the remote device and create a save file, Drivesync will pick up the changed file and sync it to your Google Drive, and when you pick the game back up on your computer the updated file will be loaded and vice versa.

If you're unfamiliar with Retroarch, check out RetroGameCorps article on it here, as well as his article/video on Android emulation. You can also use this method with standalone emulators outside of Retroarch, but it works best with consoles that have singular, simple save files with small file sizes.