manual renewals with Digicert has been a pain in the ass. If anyone has experience with their automated option I’d love to hear it.

Aren’t they RFC8666-compatible?

Yep, seems so:

ACME Directory URLs – Get certificate-level automation for Extended Validation (EV) and Organization Validated (OV) certificates. Manage multiple ACME clients, running on Windows or Linux so you can efficiently automate certificate delivery regardless of the quantity of certificates you’re managing. Improve the security of using ACME in your network through our CertCentral discovery sensors. The sensor is an extra layer of security, ensuring the ACME client doesn’t directly speak to an unsecure third party.

If you search for RFC8666 or ACME, you may find a tool you can use that may be compatible for renewing Digicert certs automatically.

I’d love to actually help, but honestly I knew the RFC offhand and googled the rest myself, so dragging the problem to ACME - like RFK dragging the carcass of a deer back to his sedan - is the best I can do for you today.