I’ve been harping for a while that Jamstack doesn’t necessarily mean throwing away your old CMS. In fact, I’d argue that Jamstack is at it’s most powerful when paired with a system that you already know, are comfortable with, and perhaps even like. You’d call that decoupling the front end.
Netlify has a webinar coming up on exactly this, featuring Alex De Winne, who is going to show you a real-world site in a live demo combining Drupal (a classic PHP & MySQL CMS that powers an absolute ton of sites) and Jamstack architecture.