Migrate data from external database to Sitefinity dynamic mo

I am using version 9.1.6110. We have recently chosen Sitefinity as our new CMS platform to host our websites.

I am trying to find a proper way to migrate data from old SQL database to sitefinity (precisely to dynamic modules). I observed that within Sitefinity we have the provision to use the dynamic module APIs to insert the data. But the question is how do I fetch the data. Is there a feature within Sitefinity on how to connect/ read external SQL database.

The other option I thought is referring the Sitefinity DLLs in the external project, fetch the data and insert into Sitefinity making use of Sitefinity's extensions (only if available)