Though Google Data catalog is in beta phase, currently it provides data catalog service support to BigQuery and cloud pub/sub services, not for Google cloud storage(in beta phase).
Is there any way using existing components/services we could build data catalog for assets stored in Google cloud storage(buckets, objects, ..) and when could we possibly expect direct support for GCS in Google data catalog.
According to Google's documentation
Tagging Cloud Storage assets (for example, buckets and objects) is unavailable in the Data Catalog beta release.
Full support for Cloud Data Catalog is scheduled for the last quarter of this year, 2019. (from October-on)
Data Catalog became GA: Data Catalog GA
And they have updated the docs for Filesets: Data Catalog Filesets
Finally if you want to create Data Catalog assets for each of your cloud storage objects, you may use this open source script: datacatalog-util which has an option to create Entries for your files.
