Here's my solution based on the link shared by @sansSpoon:
You can use this python lib: FinderSidebarEditor
Simply put it in your python path then in python, you can edit your Finder Sidebar easily:
#!/usr/bin/python
from FinderSidebarEditor import FinderSidebar # Import the module
sidebar = FinderSidebar() # Create a Finder sidebar instance to act on.
sidebar.remove("All My Files") # Remove 'All My Files' favorite from sidebar
sidebar.remove("iCloud") # Remove 'iCloud' favorite from sidebar
sidebar.add("/Library") # Add '/Library' favorite to sidebar
sidebar.add("/SomeShare", uri="smb://shares") # Mount 'smb://shares/SomeShare' to '/Volumes/SomeShare' and add as favorite to sidebar
sidebar.add("/SomeOtherShare", uri="afp://username:pw@server") # Mount pw protected 'afp://server/SomeOtherShare' to '/Volumes/SomeOtherShare' and add as favorite to sidebar
sidebar.move("Library", "Applications") # Move 'Library' favorite to slot just below 'Applications'
plistBuddy
. Depending on your OS version (I'm assuming 10.13), this might (or might not) be of help: jamf.com/jamf-nation/discussions/20218/the-slftool-thread. The file you want to change is:~/Library/Application\ Support/com.apple.sharedfilelist/com.apple.LSSharedFileList.FavoriteVolumes.sfl2