I would love to see a BPMN compliant workflow engine incorporated into Frappe.
BPMN is an open standard (https://www.omg.org/bpmn/) and the de facto foundation for most enterprise strength process automation tools.
This idea has been discussed many times on this forum:
My organisation started off using Camunda, then migrated all elementary workflows to N8N, and recently transferred most of the remaining Camunda processes to Spiff. Spiff is not as yet a complete replacement for Camunda, but suffice in most scenarios. We use the open source bpmn.io modeller and then execute the models on Spiff.
It would be a god-send to incorporate the bpmn.io modeller into Frappe / ERPNext and bundle the Spiff engine into Frappe.