Sync without GUI but live (inotify)

I know the nextcloudcmd (

But that is not what I am looking for.

I am looking for a linux service which is running via systemd and which syncs changes soon.

This implies that running nextcloudcmd again and again is not a solution.

Starting nextcloudcmd via a simple inotify-script is not really a solution, since this produces a lot of useless IO if the directory is huge and a lot of small changes happen.

The nextcloud desktop client has already solved this.

Is there no way to make this smart algorithm available via a linux systemd service?

Related question at serverfault:

There is no solution besides nextcloudcmd AFAIK.