is there a way to see in the normal file view, that a file or folder has comments? or even tags? Currently I always have to open the details page to check it.
No, unfortunately not. There’s no setting in the Files app for a view with opened details.
At least an indicator (icon) would be helpful.
But you can file a feature request on GitHub: https://github.com/nextcloud/server/issues
(I haven’t found a request for that feature.)