Version an already trained custom model on Model Registry

[LiviaPimentelCVER]

Hi, everyone!

I trained a model using scikit-learn, and saved it as a pickle file, stored in a GCS bucket. I was wondering... how can I version this model using model registry since it is already trained?

In my case, I have the option of using Cloud Run for this (a cloud run container that runs a retraining task every week), but I want to start doing it on Vertex AI.

After reading some articles about Vertex AI Model Registry, I concluded that the model must be firstly trained using a custom training job, and, just after that, we can begin its versioning on Model Registry. Is this correct?