but GitTower does not yet have VS Code as an option for diff and merge tools. but they allow adding your own by creating a .plist file.
https://www.git-tower.com/help/guides/integration/custom-diff-tools/mac
~/Library/Application Support/com.fournova.Tower3/CompareTools/
you may need to make the vscode.sh file executable by running
chmod +x ~/Library/Application Support/com.fournova.Tower3/CompareTools/vscode.sh