Does Oracle have much growth of their core RDBMS database product

Not really, and Oracle has clearly known that too for a decade.

They tried a pivot into cloud (they did a similar thing with Oracle Linux decades ago), and did a similar pivot into the Healthcare IT space over the past decade.

HIPAA-like regulation for healthcare info that coincidentally only Oracle DB complies with

It's a competitive space.

Epic, Microsoft, AWS, and other companies can also meet those RFCs.