Yes, you can use the example of embeddedstore or pgsqlstore in the directory you pointed out. Basically, the new storage will need to implement all of the API methods in go/v1beta1/api. One of the medium-term plans is to move specific storage implementations out of the grafeas/grafeas project, for more information see
https://github.com/grafeas/grafeas/issues/341. So it'd be best if you started a separate project with the implementation of the Grafeas API methods, and you could contribute the instructions on how to do this going forward. Happy to help with any other questions in the meantime.