I created a simple Finder Sync (FinderSync) extension (appex) and it comes by default with App Sandbox ON (in .entitlements com.apple.security.app-sandbox true).
Everything works fine but I need to access a specific folder on the macOS via this extension and I cannot do that with the Sandbox on.
I disabled the sandbox but the extension is not loaded anymore in Finder. Any thoughts on this? Any workarounds?
Finder Sync extensions must be sandboxed. I couldn't find this requirement explicitly documented anywhere, but the following error appears in your system log if it's not sandboxed:
pkd[255]: ignoring mis-configured plug-in at /Applications/Liferay\ Sync.app/Contents/PlugIns/LiferayFinderSync.appex: plug-ins must be sandboxed
If you need to access a folder outside your application's container, you can use temporary exception entitlements like "com.apple.security.temporary-exception.files.home-relative-path.read-only". Note that apps submitted to the Mac App Store using these entitlements will likely be rejected.