Email and/or Teams Web Hook would be great for being notified if a new application is added to the catalog or updated, so that those with access to the Publisher server can determine to run an out-of-band sync, or if they need to confirm a new product/etc., is selected in the publisher for syncing. Present Custom Apps users need to notify those with server/publisher access when these changes are made, so it'd be helpful to take one step out of the process.