Do not listen to people who say Dell systems can only boot OS X/macOS with Clover. They booted the OS without issues with Chameleon, Enoch and continue do so with OpenCore or Clover of course. Your E5530 may be getting a little old bit it will boot and run Big Sur with OC without problem. I invite you to look at my OpenCore-based E6230 Big Sur guide available in the Guides section; I trust it'll re-assure you. Latitude E6x30 are 95% identical to your E5530 model.