Old question but I want to share my solution in case it helps someone in future.
You can use the ln(aka link) command to create some hard links that keep track with latest iOS simulator sandbox files.
For example, you can create a "SimulatorDB" folder on your Desktop, then run your application and get the latest Core Data sqlite file's path inside Sandbox, then run these 3 commands to create 3 hard links:
ln /{your-app-container-path}/Library/Application\ Support/App.sqlite ~/Desktop/SimulatorDB/App.sqlite
ln /{your-app-container-path}/Library/Application\ Support/App.sqlite-shm ~/Desktop/SimulatorDB/App.sqlite-shm
ln /{your-app-container-path}/Library/Application\ Support/App.sqlite-wal ~/Desktop/SimulatorDB/App.sqlite-wal
Then config your DB browser software to connect ~/Desktop/SimulatorDB/App.sqlite directly.
Notes:
This works fine only on small amount of files, if you need to keep track on a sandbox folder with many files, the APFS seems not supporting this operation:
https://github.com/selkhateeb/hardlink/issues/31#issuecomment-332993819
There is some tools for create hard link on directory in macOS, but I haven't try them yet:
What is the Unix command to create a hardlink to a directory in OS X?